Repository: angeloc/simplemodbusng Branch: master Commit: 1079f442a559 Files: 17 Total size: 119.3 KB Directory structure: gitextract_8ia3zrgx/ ├── .github/ │ └── FUNDING.yml ├── README.md ├── SimpleModbusMaster/ │ ├── SimpleModbusMaster.cpp │ ├── SimpleModbusMaster.h │ ├── examples/ │ │ └── SimpleModbusMasterExample/ │ │ └── SimpleModbusMasterExample.ino │ └── keywords.txt ├── SimpleModbusMasterSoftwareSerial/ │ ├── SimpleModbusMasterSoftwareSerial.cpp │ └── SimpleModbusMasterSoftwareSerial.h ├── SimpleModbusSlave/ │ ├── SimpleModbusSlave.cpp │ ├── SimpleModbusSlave.h │ ├── examples/ │ │ └── SimpleModbusSlaveExample/ │ │ └── SimpleModbusSlaveExample.ino │ └── keywords.txt ├── SimpleModbusSlaveSoftwareSerial/ │ ├── SimpleModbusSlaveSoftwareSerial.cpp │ ├── SimpleModbusSlaveSoftwareSerial.h │ ├── examples/ │ │ └── SimpleModbusTinyExample/ │ │ └── SimpleModbusTinyExample.ino │ └── keywords.txt └── gpl-3.0.txt ================================================ FILE CONTENTS ================================================ ================================================ FILE: .github/FUNDING.yml ================================================ custom: https://paypal.me/angelocomp/10 ================================================ FILE: README.md ================================================ # SimpleModbus NG SimpleModbus is a collection of Arduino libraries that enables you to communicate serially using the Modicon Modbus RTU protocol. This project was born as an updated version of http://code.google.com/p/simple-modbus/ by Bester Juan because it lacks support for commands other than 3 and 16. More important the code is now on github, so you can contribute more easily. This projects is actively maintained, so feel free to ask for features or reporting bugs! ## Features This library adds support for command 6 and provides a more extensive support for arduino pins. The goal of the project is to support all usable MODBUS commands on arduino and expose all arduino pins so you can use an arduino as an advanced automation controller for both analog/digital in/out. NEW: Support for SoftwareSerial, really useful on AtTiny85. You can find both library and an example that works reliable on attiny85 microcontroller. ## Usage Simply copy the SimpleModbusMaster or SimpleModbusSlave or both into your Arduino IDE **libraries** folder. Than restart the ide and open the corresponding example into the example_master or example_slave folder. ================================================ FILE: SimpleModbusMaster/SimpleModbusMaster.cpp ================================================ #include "SimpleModbusMaster.h" #define BUFFER_SIZE 128 // modbus specific exceptions #define ILLEGAL_FUNCTION 1 #define ILLEGAL_DATA_ADDRESS 2 #define ILLEGAL_DATA_VALUE 3 unsigned char transmission_ready_Flag; unsigned char messageOkFlag, messageErrFlag; unsigned char retry_count; unsigned char TxEnablePin; // frame[] is used to recieve and transmit packages. // The maximum number of bytes in a modbus packet is 256 bytes // This is limited to the serial buffer of 128 bytes unsigned char frame[BUFFER_SIZE]; unsigned int timeout, polling; unsigned int T1_5; // inter character time out in microseconds unsigned int T3_5; // frame delay in microseconds unsigned long previousTimeout, previousPolling; unsigned int total_no_of_packets; Packet* packet; // current packet // function definitions void constructPacket(); void checkResponse(); void check_F3_data(unsigned char buffer); void check_F16_data(); unsigned char getData(); void check_packet_status(); unsigned int calculateCRC(unsigned char bufferSize); void sendPacket(unsigned char bufferSize); unsigned int modbus_update(Packet* packets) { // Initialize the connection_status variable to the // total_no_of_packets. This value cannot be used as // an index (and normally you won't). Returning this // value to the main skecth informs the user that the // previously scanned packet has no connection error. unsigned int connection_status = total_no_of_packets; if (transmission_ready_Flag) { static unsigned int packet_index; unsigned int failed_connections = 0; unsigned char current_connection; do { if (packet_index == total_no_of_packets) // wrap around to the beginning packet_index = 0; // proceed to the next packet packet = &packets[packet_index]; // get the current connection status current_connection = packet->connection; if (!current_connection) { connection_status = packet_index; // If all the connection attributes are false return // immediately to the main sketch if (++failed_connections == total_no_of_packets) return connection_status; } packet_index++; } while (!current_connection); // while a packet has no connection get the next one constructPacket(); } checkResponse(); check_packet_status(); return connection_status; } void constructPacket() { transmission_ready_Flag = 0; // disable the next transmission packet->requests++; frame[0] = packet->id; frame[1] = packet->function; frame[2] = packet->address >> 8; // address Hi frame[3] = packet->address & 0xFF; // address Lo frame[4] = packet->no_of_registers >> 8; // no_of_registers Hi frame[5] = packet->no_of_registers & 0xFF; // no_of_registers Lo unsigned int crc16; // construct the frame according to the modbus function if (packet->function == PRESET_MULTIPLE_REGISTERS) { unsigned char no_of_bytes = packet->no_of_registers * 2; unsigned char frameSize = 9 + no_of_bytes; // first 7 bytes of the array + 2 bytes CRC+ noOfBytes frame[6] = no_of_bytes; // number of bytes unsigned char index = 7; // user data starts at index 7 unsigned int temp; unsigned char no_of_registers = packet->no_of_registers; for (unsigned char i = 0; i < no_of_registers; i++) { temp = packet->register_array[i]; // get the data frame[index] = temp >> 8; index++; frame[index] = temp & 0xFF; index++; } crc16 = calculateCRC(frameSize - 2); frame[frameSize - 2] = crc16 >> 8; // split crc into 2 bytes frame[frameSize - 1] = crc16 & 0xFF; sendPacket(frameSize); if (packet->id == 0) { // check broadcast id messageOkFlag = 1; // message successful, there will be no response on a broadcast previousPolling = millis(); // start the polling delay } } else { // READ_HOLDING_REGISTERS is assumed crc16 = calculateCRC(6); // the first 6 bytes of the frame is used in the CRC calculation frame[6] = crc16 >> 8; // crc Lo frame[7] = crc16 & 0xFF; // crc Hi sendPacket(8); // a request with function 3, 4 & 6 is always 8 bytes in size } } void checkResponse() { if (!messageOkFlag && !messageErrFlag) { // check for response unsigned char buffer = getData(); if (buffer > 0) { // if there's something in the buffer continue if (frame[0] == packet->id) { // check id returned // to indicate an exception response a slave will 'OR' // the requested function with 0x80 if ((frame[1] & 0x80) == 0x80) { // exctract 0x80 // the third byte in the exception response packet is the actual exception switch (frame[2]) { case ILLEGAL_FUNCTION: packet->illegal_function++; break; case ILLEGAL_DATA_ADDRESS: packet->illegal_data_address++; break; case ILLEGAL_DATA_VALUE: packet->illegal_data_value++; break; default: packet->misc_exceptions++; } messageErrFlag = 1; // set an error previousPolling = millis(); // start the polling delay } else { // the response is valid if (frame[1] == packet->function) { // check function number returned // receive the frame according to the modbus function if (packet->function == PRESET_MULTIPLE_REGISTERS) check_F16_data(); else // READ_HOLDING_REGISTERS is assumed check_F3_data(buffer); } else { // incorrect function number returned packet->incorrect_function_returned++; messageErrFlag = 1; // set an error previousPolling = millis(); // start the polling delay } } // check exception response } else { // incorrect id returned packet->incorrect_id_returned++; messageErrFlag = 1; // set an error previousPolling = millis(); // start the polling delay } } // check buffer } // check message booleans } // checks the time out and polling delay and if a message has been recieved succesfully void check_packet_status() { unsigned char pollingFinished = (millis() - previousPolling) > polling; if (messageOkFlag && pollingFinished) { // if a valid message was recieved and the polling delay has expired clear the flag messageOkFlag = 0; packet->successful_requests++; // transaction sent successfully packet->retries = 0; // if a request was successful reset the retry counter transmission_ready_Flag = 1; } // if an error message was recieved and the polling delay has expired clear the flag if (messageErrFlag && pollingFinished) { messageErrFlag = 0; // clear error flag packet->retries++; transmission_ready_Flag = 1; } // if the timeout delay has past clear the slot number for next request if (!transmission_ready_Flag && ((millis() - previousTimeout) > timeout)) { packet->timeout++; packet->retries++; transmission_ready_Flag = 1; } // if the number of retries have reached the max number of retries // allowable, stop requesting the specific packet if (packet->retries == retry_count) { packet->connection = 0; packet->retries = 0; } if (transmission_ready_Flag) { // update the total_errors atribute of the // packet before requesting a new one packet->total_errors = packet->timeout + packet->incorrect_id_returned + packet->incorrect_function_returned + packet->incorrect_bytes_returned + packet->checksum_failed + packet->buffer_errors + packet->illegal_function + packet->illegal_data_address + packet->illegal_data_value; } } void check_F3_data(unsigned char buffer) { unsigned char no_of_registers = packet->no_of_registers; unsigned char no_of_bytes = no_of_registers * 2; if (frame[2] == no_of_bytes) { // check number of bytes returned // combine the crc Low & High bytes unsigned int recieved_crc = ((frame[buffer - 2] << 8) | frame[buffer - 1]); unsigned int calculated_crc = calculateCRC(buffer - 2); if (calculated_crc == recieved_crc) { // verify checksum unsigned char index = 3; for (unsigned char i = 0; i < no_of_registers; i++) { // start at the 4th element in the recieveFrame and combine the Lo byte packet->register_array[i] = (frame[index] << 8) | frame[index + 1]; index += 2; } messageOkFlag = 1; // message successful } else { // checksum failed packet->checksum_failed++; messageErrFlag = 1; // set an error } // start the polling delay for messageOkFlag & messageErrFlag previousPolling = millis(); } else { // incorrect number of bytes returned packet->incorrect_bytes_returned++; messageErrFlag = 1; // set an error previousPolling = millis(); // start the polling delay } } void check_F16_data() { unsigned int recieved_address = ((frame[2] << 8) | frame[3]); unsigned int recieved_registers = ((frame[4] << 8) | frame[5]); unsigned int recieved_crc = ((frame[6] << 8) | frame[7]); // combine the crc Low & High bytes unsigned int calculated_crc = calculateCRC(6); // only the first 6 bytes are used for crc calculation // check the whole packet if (recieved_address == packet->address && recieved_registers == packet->no_of_registers && recieved_crc == calculated_crc) messageOkFlag = 1; // message successful else { packet->checksum_failed++; messageErrFlag = 1; } // start the polling delay for messageOkFlag & messageErrFlag previousPolling = millis(); } // get the serial data from the buffer unsigned char getData() { unsigned char buffer = 0; unsigned char overflowFlag = 0; while (Serial.available()) { // The maximum number of bytes is limited to the serial buffer size of 128 bytes // If more bytes is received than the BUFFER_SIZE the overflow flag will be set and the // serial buffer will be red untill all the data is cleared from the receive buffer, // while the slave is still responding. if (overflowFlag) Serial.read(); else { if (buffer == BUFFER_SIZE) overflowFlag = 1; frame[buffer] = Serial.read(); buffer++; } delayMicroseconds(T1_5); // inter character time out } // The minimum buffer size from a slave can be an exception response of 5 bytes // If the buffer was partialy filled clear the buffer. // The maximum number of bytes in a modbus packet is 256 bytes. // The serial buffer limits this to 128 bytes. // If the buffer overflows than clear the buffer and set // a packet error. if ((buffer > 0 && buffer < 5) || overflowFlag) { buffer = 0; packet->buffer_errors++; messageErrFlag = 1; // set an error previousPolling = millis(); // start the polling delay } return buffer; } void modbus_configure(long baud, unsigned int _timeout, unsigned int _polling, unsigned char _retry_count, unsigned char _TxEnablePin, Packet* _packet, unsigned int _total_no_of_packets) { Serial.begin(baud); if (_TxEnablePin > 1) { // pin 0 & pin 1 are reserved for RX/TX. To disable set _TxEnablePin < 2 TxEnablePin = _TxEnablePin; pinMode(TxEnablePin, OUTPUT); digitalWrite(TxEnablePin, LOW); } // Modbus states that a baud rate higher than 19200 must use a fixed 750 us // for inter character time out and 1.75 ms for a frame delay. // For baud rates below 19200 the timeing is more critical and has to be calculated. // E.g. 9600 baud in a 10 bit packet is 960 characters per second // In milliseconds this will be 960characters per 1000ms. So for 1 character // 1000ms/960characters is 1.04167ms per character and finaly modbus states an // intercharacter must be 1.5T or 1.5 times longer than a normal character and thus // 1.5T = 1.04167ms * 1.5 = 1.5625ms. A frame delay is 3.5T. if (baud > 19200) { T1_5 = 750; T3_5 = 1750; } else { T1_5 = 15000000/baud; // 1T * 1.5 = T1.5 T3_5 = 35000000/baud; // 1T * 3.5 = T3.5 } // initialize connection status of each packet for (unsigned char i = 0; i < _total_no_of_packets; i++) { _packet->connection = 1; _packet++; } // initialize transmission_ready_Flag = 1; messageOkFlag = 0; messageErrFlag = 0; timeout = _timeout; polling = _polling; retry_count = _retry_count; TxEnablePin = _TxEnablePin; total_no_of_packets = _total_no_of_packets; previousTimeout = 0; previousPolling = 0; } unsigned int calculateCRC(unsigned char bufferSize) { unsigned int temp, temp2, flag; temp = 0xFFFF; for (unsigned char i = 0; i < bufferSize; i++) { temp = temp ^ frame[i]; for (unsigned char j = 1; j <= 8; j++) { flag = temp & 0x0001; temp >>= 1; if (flag) temp ^= 0xA001; } } // Reverse byte order. temp2 = temp >> 8; temp = (temp << 8) | temp2; temp &= 0xFFFF; return temp; // the returned value is already swopped - crcLo byte is first & crcHi byte is last } void sendPacket(unsigned char bufferSize) { if (TxEnablePin > 1) digitalWrite(TxEnablePin, HIGH); for (unsigned char i = 0; i < bufferSize; i++) Serial.write(frame[i]); Serial.flush(); // allow a frame delay to indicate end of transmission delayMicroseconds(T3_5); if (TxEnablePin > 1) digitalWrite(TxEnablePin, LOW); previousTimeout = millis(); // initialize timeout delay } ================================================ FILE: SimpleModbusMaster/SimpleModbusMaster.h ================================================ #ifndef SIMPLE_MODBUS_MASTER_H #define SIMPLE_MODBUS_MASTER_H /* SimpleModbusMaster allows you to communicate to any slave using the Modbus RTU protocol. To communicate with a slave you need to create a packet that will contain all the information required to communicate to the slave. There are numerous counters for easy diagnostic. These are variables already implemented in a packet. You can set and clear these variables as needed. There are general modbus information counters: requests - contains the total requests to a slave successful_requests - contains the total successful requests total_errors - contains the total errors as a sum timeout - contains the total time out errors incorrect_id_returned - contains the total incorrect id returned errors incorrect_function_returned - contains the total incorrect function returned errors incorrect_bytes_returned - contains the total incorrect bytes returned errors checksum_failed - contains the total checksum failed errors buffer_errors - contains the total buffer errors And there are modbus specific exception counters: illegal_function - contains the total illegal_function errors illegal_data_address - contains the total illegal_data_address errors illegal_data_value - contains the total illegal_data_value errors misc_exceptions - contains the total miscellaneous returned exceptions And finally there is variable called "connection" that at any given moment contains the current connection status of the packet. If true then the connection is active. If false then communication will be stopped on this packet untill the programmer sets the connections variable to true explicitly. The reason for this is because of the time out involved in modbus communication. EACH faulty slave that's not communicating will slow down communication on the line with the time out value. E.g. Using a time out of 1500ms, if you have 10 slaves and 9 of them stops communicating the latency burden placed on communication will be 1500ms * 9 = 13,5 seconds!!!! In addition to this when all the packets are scanned and all of them have a false connection a value is returned from modbus_port() to inform you something is wrong with the port. This is most likely to happen when there is something physically wrong with the RS485 line. This is only for information. You have to explicitly set each packets connection attribute to false. Packets scanning and communication will automatically revert to normal. All the error checking, updating and communication multitasking takes place in the background! In general to communicate with to a slave using modbus RTU you will request information using the specific slave id, the function request, the starting address and lastly the number of registers to request. Function 3 & 16 are supported. In addition to this broadcasting (id = 0) is supported for function 16. Constants are provided for: Function 3 - READ_HOLDING_REGISTERS Function 16 - PRESET_MULTIPLE_REGISTERS Note: The Arduino serial ring buffer is 128 bytes or 64 registers. Most of the time you will connect the arduino to a master via serial using a MAX485 or similar. In a function 3 request the master will attempt to read from your slave and since 5 bytes is already used for ID, FUNCTION, NO OF BYTES and two BYTES CRC the master can only request 122 bytes or 61 registers. In a function 16 request the master will attempt to write to your slave and since a 9 bytes is already used for ID, FUNCTION, ADDRESS, NO OF REGISTERS, NO OF BYTES and two BYTES CRC the master can only write 118 bytes or 59 registers. Using the FTDI USB to Serial converter the maximum bytes you can send is limited to its internal buffer which is 60 bytes or 30 unsigned int registers. Thus: In a function 3 request the master will attempt to read from your slave and since 5 bytes is already used for ID, FUNCTION, NO OF BYTES and two BYTES CRC the master can only request 54 bytes or 27 registers. In a function 16 request the master will attempt to write to your slave and since a 9 bytes is already used for ID, FUNCTION, ADDRESS, NO OF REGISTERS, NO OF BYTES and two BYTES CRC the master can only write 50 bytes or 25 registers. Since it is assumed that you will mostly use the Arduino to connect to a master without using a USB to Serial converter the internal buffer is set the same as the Arduino Serial ring buffer which is 128 bytes. */ #include "Arduino.h" #define READ_HOLDING_REGISTERS 3 #define PRESET_MULTIPLE_REGISTERS 16 typedef struct { // specific packet info unsigned char id; unsigned char function; unsigned int address; unsigned int no_of_registers; unsigned int* register_array; // modbus information counters unsigned int requests; unsigned int successful_requests; unsigned long total_errors; unsigned int retries; unsigned int timeout; unsigned int incorrect_id_returned; unsigned int incorrect_function_returned; unsigned int incorrect_bytes_returned; unsigned int checksum_failed; unsigned int buffer_errors; // modbus specific exception counters unsigned int illegal_function; unsigned int illegal_data_address; unsigned int illegal_data_value; unsigned char misc_exceptions; // connection status of packet unsigned char connection; } Packet; typedef Packet* packetPointer; // function definitions unsigned int modbus_update(Packet* packets); void modbus_configure(long baud, unsigned int _timeout, unsigned int _polling, unsigned char _retry_count, unsigned char _TxEnablePin, Packet* packets, unsigned int _total_no_of_packets); #endif ================================================ FILE: SimpleModbusMaster/examples/SimpleModbusMasterExample/SimpleModbusMasterExample.ino ================================================ #include /* To communicate with a slave you need to create a packet that will contain all the information required to communicate to that slave. There are numerous counters for easy diagnostic. These are variables already implemented in a packet. You can set and clear these variables as needed. There are general modbus information counters: requests - contains the total requests to a slave successful_requests - contains the total successful requests total_errors - contains the total errors as a sum timeout - contains the total time out errors incorrect_id_returned - contains the total incorrect id returned errors incorrect_function_returned - contains the total incorrect function returned errors incorrect_bytes_returned - contains the total incorrect bytes returned errors checksum_failed - contains the total checksum failed errors buffer_errors - contains the total buffer errors And there are modbus specific exception counters: illegal_function - contains the total illegal function errors illegal_data_address - contains the total illegal data_address errors illegal_data_value - contains the total illegal data value errors misc_exceptions - contains the total miscellaneous returned exceptions And finally there is a variable called "connection" that at any given moment contains the current connection status of the packet. If true then the connection is active if false then communication will be stopped on this packet untill the programmer sets the "connection" variable to true explicitly. The reason for this is because of the time out involved in modbus communication. EACH faulty slave that's not communicating will slow down communication on the line with the time out value. E.g. Using a time out of 1500ms, if you have 10 slaves and 9 of them stops communicating the latency burden placed on communication will be 1500ms * 9 = 13,5 seconds!!!! modbus_update() returns the previously scanned false connection. You can use this as the index to your packet array to find out if the connection has failed in that packet and then react to it. You can then try to re-enable the connecion by setting the packet->connection attribute to true. The index will only be available for one loop cycle, after that it's cleared and ready to return the next false connection index if there is one else it will return the packet array size indicating everything is ok. All the error checking, updating and communication multitasking takes place in the background! In general to communicate with to a slave using modbus RTU you will request information using the specific slave id, the function request, the starting address and lastly the number of registers to request. Function 3 and 16 are supported. In addition to this broadcasting (id = 0) is supported on function 16. Constants are provided for: Function 3 - READ_HOLDING_REGISTERS Function 16 - PRESET_MULTIPLE_REGISTERS The example sketch will read a packet consisting of 9 registers from address 0 using function 3 from the SimpleModbusSlave example and then write another packet containing a value to toggle the led.s */ // led to indicate that a communication error is present #define connection_error_led 13 //////////////////// Port information /////////////////// #define baud 115200 #define timeout 1000 #define polling 200 // the scan rate // If the packets internal retry register matches // the set retry count then communication is stopped // on that packet. To re-enable the packet you must // set the "connection" variable to true. #define retry_count 10 // used to toggle the receive/transmit pin on the driver #define TxEnablePin 2 // This is the easiest way to create new packets // Add as many as you want. TOTAL_NO_OF_PACKETS // is automatically updated. enum { PACKET1, PACKET2, // leave this last entry TOTAL_NO_OF_PACKETS }; // Create an array of Packets for modbus_update() Packet packets[TOTAL_NO_OF_PACKETS]; // Create a packetPointer to access each packet // individually. This is not required you can access // the array explicitly. E.g. packets[PACKET1].id = 2; // This does become tedious though... packetPointer packet1 = &packets[PACKET1]; packetPointer packet2 = &packets[PACKET2]; // The data from the PLC will be stored // in the regs array unsigned int regs[9]; unsigned int write_regs[1]; unsigned long last_toggle = 0; void setup() { // read 3 registers starting at address 0 packet1->id = 2; packet1->function = READ_HOLDING_REGISTERS; packet1->address = 0; packet1->no_of_registers = 9; packet1->register_array = regs; // write the 9 registers to the PLC starting at address 3 packet2->id = 2; packet2->function = PRESET_MULTIPLE_REGISTERS; packet2->address = 6; packet2->no_of_registers = 1; packet2->register_array = write_regs; // Initialize communication settings etc... modbus_configure(baud, timeout, polling, retry_count, TxEnablePin, packets, TOTAL_NO_OF_PACKETS); pinMode(connection_error_led, OUTPUT); } void loop() { unsigned int connection_status = modbus_update(packets); if (millis() - last_toggle > 1000) { last_toggle = millis(); write_regs[0] = led_on; } if (connection_status != TOTAL_NO_OF_PACKETS) { digitalWrite(connection_error_led, HIGH); // You could re-enable the connection by: //packets[connection_status].connection = true; } else { digitalWrite(connection_error_led, LOW); } } ================================================ FILE: SimpleModbusMaster/keywords.txt ================================================ Packet KEYWORD1 packetPointer KEYWORD1 modbus_configure KEYWORD2 modbus_port KEYWORD2 ###### Constants ###### READ_HOLDING_REGISTERS LITERAL1 PRESET_MULTIPLE_REGISTERS LITERAL1 ================================================ FILE: SimpleModbusMasterSoftwareSerial/SimpleModbusMasterSoftwareSerial.cpp ================================================ #include "SimpleModbusMasterSoftwareSerial.h" #define BUFFER_SIZE 128 // modbus specific exceptions #define ILLEGAL_FUNCTION 1 #define ILLEGAL_DATA_ADDRESS 2 #define ILLEGAL_DATA_VALUE 3 unsigned char transmission_ready_Flag; unsigned char messageOkFlag, messageErrFlag; unsigned char retry_count; unsigned char TxEnablePin; // frame[] is used to recieve and transmit packages. // The maximum number of bytes in a modbus packet is 256 bytes // This is limited to the serial buffer of 128 bytes unsigned char frame[BUFFER_SIZE]; unsigned int timeout, polling; unsigned int T1_5; // inter character time out in microseconds unsigned int T3_5; // frame delay in microseconds unsigned long previousTimeout, previousPolling; unsigned int total_no_of_packets; Packet* packet; // current packet SoftwareSerial* _port; // function definitions void constructPacket(); void checkResponse(); void check_F3_data(unsigned char buffer); void check_F16_data(); unsigned char getData(); void check_packet_status(); unsigned int calculateCRC(unsigned char bufferSize); void sendPacket(unsigned char bufferSize); // use this function create packets void modbus_packet_init(Packet *packet, unsigned char id, unsigned char function, unsigned int dest_register, unsigned int num_registers, unsigned int *reg) { packet->id = id; packet->function = function; packet->address = dest_register; // first slave register to write to packet->no_of_registers = num_registers; // number of registers to write packet->register_array = reg; // first master register to read from } unsigned int modbus_update(Packet* packets) { // Initialize the connection_status variable to the // total_no_of_packets. This value cannot be used as // an index (and normally you won't). Returning this // value to the main skecth informs the user that the // previously scanned packet has no connection error. unsigned int connection_status = total_no_of_packets; if (transmission_ready_Flag) { static unsigned int packet_index; unsigned int failed_connections = 0; unsigned char current_connection; do { if (packet_index == total_no_of_packets) // wrap around to the beginning packet_index = 0; // proceed to the next packet packet = &packets[packet_index]; // get the current connection status current_connection = packet->connection; if (!current_connection) { connection_status = packet_index; // If all the connection attributes are false return // immediately to the main sketch if (++failed_connections == total_no_of_packets) return connection_status; } packet_index++; }while (!current_connection); // while a packet has no connection get the next one constructPacket(); } checkResponse(); check_packet_status(); return connection_status; } void constructPacket() { unsigned int crc16; transmission_ready_Flag = 0; // disable the next transmission packet->requests++; frame[0] = packet->id; frame[1] = packet->function; frame[2] = packet->address >> 8; // address Hi frame[3] = packet->address & 0xFF; // address Lo frame[4] = packet->no_of_registers >> 8; // no_of_registers Hi frame[5] = packet->no_of_registers & 0xFF; // no_of_registers Lo // construct the frame according to the modbus function if (packet->function == PRESET_MULTIPLE_REGISTERS) { unsigned char no_of_bytes = packet->no_of_registers * 2; unsigned char frameSize = 9 + no_of_bytes; // first 7 bytes of the array + 2 bytes CRC+ noOfBytes frame[6] = no_of_bytes; // number of bytes unsigned char index = 7; // user data starts at index 7 unsigned int temp; // should be unsigned int but we will never send more than 255 registers in 1 packet unsigned char no_of_registers = packet->no_of_registers; for (unsigned char i = 0; i < no_of_registers; i++) { temp = packet->register_array[i]; // get the data frame[index] = temp >> 8; index++; frame[index] = temp & 0xFF; index++; } crc16 = calculateCRC(frameSize - 2); frame[frameSize - 2] = crc16 >> 8; // split crc into 2 bytes frame[frameSize - 1] = crc16 & 0xFF; sendPacket(frameSize); if (packet->id == 0) // check broadcast id { messageOkFlag = 1; // message successful, there will be no response on a broadcast previousPolling = millis(); // start the polling delay } } else // READ_HOLDING_REGISTERS is assumed { crc16 = calculateCRC(6); // the first 6 bytes of the frame is used in the CRC calculation frame[6] = crc16 >> 8; // crc Lo frame[7] = crc16 & 0xFF; // crc Hi sendPacket(8); // a request with function 3, 4 & 6 is always 8 bytes in size } } void checkResponse() { if (!messageOkFlag && !messageErrFlag) // check for response { unsigned char buffer = getData(); if (buffer > 0) // if there's something in the buffer continue { if (frame[0] == packet->id) // check id returned { // to indicate an exception response a slave will 'OR' // the requested function with 0x80 if ((frame[1] & 0x80) == 0x80) // exctract 0x80 { // the third byte in the exception response packet is the actual exception switch (frame[2]) { case ILLEGAL_FUNCTION: packet->illegal_function++; break; case ILLEGAL_DATA_ADDRESS: packet->illegal_data_address++; break; case ILLEGAL_DATA_VALUE: packet->illegal_data_value++; break; default: packet->misc_exceptions++; } messageErrFlag = 1; // set an error previousPolling = millis(); // start the polling delay } else // the response is valid { if (frame[1] == packet->function) // check function number returned { // receive the frame according to the modbus function if (packet->function == PRESET_MULTIPLE_REGISTERS) check_F16_data(); else // READ_HOLDING_REGISTERS is assumed check_F3_data(buffer); } else // incorrect function number returned { packet->incorrect_function_returned++; messageErrFlag = 1; // set an error previousPolling = millis(); // start the polling delay } } // check exception response } else // incorrect id returned { packet->incorrect_id_returned++; messageErrFlag = 1; // set an error previousPolling = millis(); // start the polling delay } } // check buffer } // check message booleans } // checks the time out and polling delay and if a message has been recieved succesfully void check_packet_status() { unsigned char pollingFinished = (millis() - previousPolling) > polling; // if a valid message was recieved and the polling delay has expired clear the flag if (messageOkFlag && pollingFinished) { messageOkFlag = 0; packet->successful_requests++; // transaction sent successfully packet->retries = 0; // if a request was successful reset the retry counter transmission_ready_Flag = 1; } // if an error message was recieved and the polling delay has expired clear the flag if (messageErrFlag && pollingFinished) { messageErrFlag = 0; // clear error flag packet->retries++; transmission_ready_Flag = 1; } // if the timeout delay has past clear the slot number for next request if (!transmission_ready_Flag && ((millis() - previousTimeout) > timeout)) { packet->timeout++; packet->retries++; transmission_ready_Flag = 1; } // if the number of retries have reached the max number of retries // allowable, stop requesting the specific packet if (packet->retries == retry_count) { packet->connection = 0; packet->retries = 0; } if (transmission_ready_Flag) { // update the total_errors atribute of the // packet before requesting a new one packet->total_errors = packet->timeout + packet->incorrect_id_returned + packet->incorrect_function_returned + packet->incorrect_bytes_returned + packet->checksum_failed + packet->buffer_errors + packet->illegal_function + packet->illegal_data_address + packet->illegal_data_value; } } void check_F3_data(unsigned char buffer) { unsigned char no_of_registers = packet->no_of_registers; unsigned char no_of_bytes = no_of_registers * 2; if (frame[2] == no_of_bytes) // check number of bytes returned { // combine the crc Low & High bytes unsigned int recieved_crc = ((frame[buffer - 2] << 8) | frame[buffer - 1]); unsigned int calculated_crc = calculateCRC(buffer - 2); if (calculated_crc == recieved_crc) // verify checksum { unsigned char index = 3; for (unsigned char i = 0; i < no_of_registers; i++) { // start at the 4th element in the recieveFrame and combine the Lo byte packet->register_array[i] = (frame[index] << 8) | frame[index + 1]; index += 2; } messageOkFlag = 1; // message successful } else // checksum failed { packet->checksum_failed++; messageErrFlag = 1; // set an error } // start the polling delay for messageOkFlag & messageErrFlag previousPolling = millis(); } else // incorrect number of bytes returned { packet->incorrect_bytes_returned++; messageErrFlag = 1; // set an error previousPolling = millis(); // start the polling delay } } void check_F16_data() { unsigned int recieved_address = ((frame[2] << 8) | frame[3]); unsigned int recieved_registers = ((frame[4] << 8) | frame[5]); unsigned int recieved_crc = ((frame[6] << 8) | frame[7]); // combine the crc Low & High bytes unsigned int calculated_crc = calculateCRC(6); // only the first 6 bytes are used for crc calculation // check the whole packet if (recieved_address == packet->address && recieved_registers == packet->no_of_registers && recieved_crc == calculated_crc) messageOkFlag = 1; // message successful else { packet->checksum_failed++; messageErrFlag = 1; } // start the polling delay for messageOkFlag & messageErrFlag previousPolling = millis(); } // get the serial data from the buffer unsigned char getData() { unsigned char buffer = 0; unsigned char overflowFlag = 0; while ((*_port).available()) { // The maximum number of bytes is limited to the serial buffer size of 128 bytes // If more bytes is received than the BUFFER_SIZE the overflow flag will be set and the // serial buffer will be red untill all the data is cleared from the receive buffer, // while the slave is still responding. if (overflowFlag) (*_port).read(); else { if (buffer == BUFFER_SIZE) overflowFlag = 1; frame[buffer] = (*_port).read(); buffer++; } delayMicroseconds(T1_5); // inter character time out } // The minimum buffer size from a slave can be an exception response of 5 bytes // If the buffer was partialy filled clear the buffer. // The maximum number of bytes in a modbus packet is 256 bytes. // The serial buffer limits this to 128 bytes. // If the buffer overflows than clear the buffer and set // a packet error. if ((buffer > 0 && buffer < 5) || overflowFlag) { buffer = 0; packet->buffer_errors++; messageErrFlag = 1; // set an error previousPolling = millis(); // start the polling delay } return buffer; } void modbus_configure(SoftwareSerial* comPort, long baud, unsigned int _timeout, unsigned int _polling, unsigned char _retry_count, unsigned char _TxEnablePin, Packet* _packet, unsigned int _total_no_of_packets) { _port = comPort; (*_port).begin(baud); // pin 0 & pin 1 are reserved for RX/TX. To disable set _TxEnablePin < 2 if (_TxEnablePin > 1) { TxEnablePin = _TxEnablePin; pinMode(TxEnablePin, OUTPUT); digitalWrite(TxEnablePin, LOW); } // Modbus states that a baud rate higher than 19200 must use a fixed 750 us // for inter character time out and 1.75 ms for a frame delay. // For baud rates below 19200 the timeing is more critical and has to be calculated. // E.g. 9600 baud in a 10 bit packet is 960 characters per second // In milliseconds this will be 960characters per 1000ms. So for 1 character // 1000ms/960characters is 1.04167ms per character and finaly modbus states an // intercharacter must be 1.5T or 1.5 times longer than a normal character and thus // 1.5T = 1.04167ms * 1.5 = 1.5625ms. A frame delay is 3.5T. if (baud > 19200) { T1_5 = 750; T3_5 = 1750; } else { T1_5 = 15000000/baud; // 1T * 1.5 = T1.5 T3_5 = 35000000/baud; // 1T * 3.5 = T3.5 } // initialize connection status of each packet for (unsigned char i = 0; i < _total_no_of_packets; i++) { _packet->connection = 1; _packet++; } // initialize transmission_ready_Flag = 1; messageOkFlag = 0; messageErrFlag = 0; timeout = _timeout; polling = _polling; retry_count = _retry_count; TxEnablePin = _TxEnablePin; total_no_of_packets = _total_no_of_packets; previousTimeout = 0; previousPolling = 0; } unsigned int calculateCRC(unsigned char bufferSize) { unsigned int temp, temp2, flag; temp = 0xFFFF; for (unsigned char i = 0; i < bufferSize; i++) { temp = temp ^ frame[i]; for (unsigned char j = 1; j <= 8; j++) { flag = temp & 0x0001; temp >>= 1; if (flag) temp ^= 0xA001; } } // Reverse byte order. temp2 = temp >> 8; temp = (temp << 8) | temp2; temp &= 0xFFFF; return temp; // the returned value is already swopped - crcLo byte is first & crcHi byte is last } void sendPacket(unsigned char bufferSize) { if (TxEnablePin > 1) digitalWrite(TxEnablePin, HIGH); for (unsigned char i = 0; i < bufferSize; i++) (*_port).write(frame[i]); // finish writing buffer to the wire, only works for HardwareSerial (*_port).flush(); // allow a frame delay to indicate end of transmission delayMicroseconds(T3_5); if (TxEnablePin > 1) digitalWrite(TxEnablePin, LOW); previousTimeout = millis(); // initialize timeout delay } ================================================ FILE: SimpleModbusMasterSoftwareSerial/SimpleModbusMasterSoftwareSerial.h ================================================ #ifndef SIMPLE_MODBUS_MASTER_H #define SIMPLE_MODBUS_MASTER_H /* SoftwareSerial has limitations and is NOT SUPPORTED ON ALL PINS. SimpleModbusMaster allows you to communicate to any slave using the Modbus RTU protocol. To communicate with a slave you need to create a packet that will contain all the information required to communicate to the slave. There are numerous counters for easy diagnostic. These are variables already implemented in a packet. You can set and clear these variables as needed. There are general modbus information counters: requests - contains the total requests to a slave successful_requests - contains the total successful requests total_errors - contains the total errors as a sum timeout - contains the total time out errors incorrect_id_returned - contains the total incorrect id returned errors incorrect_function_returned - contains the total incorrect function returned errors incorrect_bytes_returned - contains the total incorrect bytes returned errors checksum_failed - contains the total checksum failed errors buffer_errors - contains the total buffer errors And there are modbus specific exception counters: illegal_function - contains the total illegal_function errors illegal_data_address - contains the total illegal_data_address errors illegal_data_value - contains the total illegal_data_value errors misc_exceptions - contains the total miscellaneous returned exceptions And finally there is variable called "connection" that at any given moment contains the current connection status of the packet. If true then the connection is active. If false then communication will be stopped on this packet untill the programmer sets the connections variable to true explicitly. The reason for this is because of the time out involved in modbus communication. EACH faulty slave that's not communicating will slow down communication on the line with the time out value. E.g. Using a time out of 1500ms, if you have 10 slaves and 9 of them stops communicating the latency burden placed on communication will be 1500ms * 9 = 13,5 seconds!!!! In addition to this when all the packets are scanned and all of them have a false connection a value is returned from modbus_port() to inform you something is wrong with the port. This is most likely to happen when there is something physically wrong with the RS485 line. This is only for information. You have to explicitly set each packets connection attribute to false. Packets scanning and communication will automatically revert to normal. All the error checking, updating and communication multitasking takes place in the background! In general to communicate with to a slave using modbus RTU you will request information using the specific slave id, the function request, the starting address and lastly the number of registers to request. Function 3 & 16 are supported. In addition to this broadcasting (id = 0) is supported for function 16. Constants are provided for: Function 3 - READ_HOLDING_REGISTERS Function 16 - PRESET_MULTIPLE_REGISTERS Note: The Arduino serial ring buffer is 128 bytes or 64 registers. Most of the time you will connect the arduino to a master via serial using a MAX485 or similar. In a function 3 request the master will attempt to read from your slave and since 5 bytes is already used for ID, FUNCTION, NO OF BYTES and two BYTES CRC the master can only request 122 bytes or 61 registers. In a function 16 request the master will attempt to write to your slave and since a 9 bytes is already used for ID, FUNCTION, ADDRESS, NO OF REGISTERS, NO OF BYTES and two BYTES CRC the master can only write 118 bytes or 59 registers. Using the FTDI USB to Serial converter the maximum bytes you can send is limited to its internal buffer which is 60 bytes or 30 unsigned int registers. Thus: In a function 3 request the master will attempt to read from your slave and since 5 bytes is already used for ID, FUNCTION, NO OF BYTES and two BYTES CRC the master can only request 54 bytes or 27 registers. In a function 16 request the master will attempt to write to your slave and since a 9 bytes is already used for ID, FUNCTION, ADDRESS, NO OF REGISTERS, NO OF BYTES and two BYTES CRC the master can only write 50 bytes or 25 registers. Since it is assumed that you will mostly use the Arduino to connect to a master without using a USB to Serial converter the internal buffer is set the same as the Arduino Serial ring buffer which is 128 bytes. */ #include "Arduino.h" #include "SoftwareSerial.h" #define READ_HOLDING_REGISTERS 3 #define PRESET_MULTIPLE_REGISTERS 16 typedef struct { // specific packet info unsigned char id; unsigned char function; unsigned int address; unsigned int no_of_registers; unsigned int* register_array; // modbus information counters unsigned int requests; unsigned int successful_requests; unsigned long total_errors; unsigned int retries; unsigned int timeout; unsigned int incorrect_id_returned; unsigned int incorrect_function_returned; unsigned int incorrect_bytes_returned; unsigned int checksum_failed; unsigned int buffer_errors; // modbus specific exception counters unsigned int illegal_function; unsigned int illegal_data_address; unsigned int illegal_data_value; unsigned char misc_exceptions; // connection status of packet unsigned char connection; }Packet; typedef Packet* packetPointer; unsigned int modbus_update(Packet* packets); void modbus_configure( SoftwareSerial* comPort, long baud, unsigned int _timeout, unsigned int _polling, unsigned char _retry_count, unsigned char _TxEnablePin, Packet* packets, unsigned int _total_no_of_packets); void modbus_packet_init( Packet *packet, unsigned char id, unsigned char function, unsigned int dest_register, unsigned int num_registers, unsigned int *reg); #endif ================================================ FILE: SimpleModbusSlave/SimpleModbusSlave.cpp ================================================ #include "SimpleModbusSlave.h" #define BUFFER_SIZE 128 // frame[] is used to recieve and transmit packages. // The maximum serial ring buffer size is 128 unsigned char frame[BUFFER_SIZE]; unsigned int holdingRegsSize; // size of the register array unsigned char broadcastFlag; unsigned char slaveID; unsigned char function; unsigned char TxEnablePin; unsigned int errorCount; unsigned int T1_5; // inter character time out unsigned int T3_5; // frame delay // function definitions void exceptionResponse(unsigned char exception); unsigned int calculateCRC(unsigned char bufferSize); void sendPacket(unsigned char bufferSize); unsigned int modbus_update(unsigned int *holdingRegs) { unsigned char buffer = 0; unsigned char overflow = 0; while (Serial.available()) { // The maximum number of bytes is limited to the serial buffer size of 128 bytes // If more bytes is received than the BUFFER_SIZE the overflow flag will be set and the // serial buffer will be red untill all the data is cleared from the receive buffer. if (overflow) Serial.read(); else { if (buffer == BUFFER_SIZE) overflow = 1; frame[buffer] = Serial.read(); buffer++; } delayMicroseconds(T1_5); // inter character time out } // If an overflow occurred increment the errorCount // variable and return to the main sketch without // responding to the request i.e. force a timeout if (overflow) return errorCount++; // The minimum request packet is 8 bytes for function 3 & 16 if (buffer > 6) { unsigned char id = frame[0]; broadcastFlag = 0; if (id == 0) broadcastFlag = 1; if (id == slaveID || broadcastFlag) { // if the recieved ID matches the slaveID or broadcasting id (0), continue unsigned int crc = ((frame[buffer - 2] << 8) | frame[buffer - 1]); // combine the crc Low & High bytes if (calculateCRC(buffer - 2) == crc) { // if the calculated crc matches the recieved crc continue function = frame[1]; unsigned int startingAddress = ((frame[2] << 8) | frame[3]); // combine the starting address bytes unsigned int no_of_registers = ((frame[4] << 8) | frame[5]); // combine the number of register bytes unsigned int maxData = startingAddress + no_of_registers; unsigned char index; unsigned char address; unsigned int crc16; // broadcasting is not supported for function 3 if (!broadcastFlag && (function == 3)) { if (startingAddress < holdingRegsSize) { // check exception 2 ILLEGAL DATA ADDRESS if (maxData <= holdingRegsSize) { // check exception 3 ILLEGAL DATA VALUE unsigned char noOfBytes = no_of_registers * 2; unsigned char responseFrameSize = 5 + noOfBytes; // ID, function, noOfBytes, (dataLo + dataHi) * number of registers, crcLo, crcHi frame[0] = slaveID; frame[1] = function; frame[2] = noOfBytes; address = 3; // PDU starts at the 4th byte unsigned int temp; for (index = startingAddress; index < maxData; index++) { temp = holdingRegs[index]; frame[address] = temp >> 8; // split the register into 2 bytes address++; frame[address] = temp & 0xFF; address++; } crc16 = calculateCRC(responseFrameSize - 2); frame[responseFrameSize - 2] = crc16 >> 8; // split crc into 2 bytes frame[responseFrameSize - 1] = crc16 & 0xFF; sendPacket(responseFrameSize); } else exceptionResponse(3); // exception 3 ILLEGAL DATA VALUE } else exceptionResponse(2); // exception 2 ILLEGAL DATA ADDRESS } else if (function == 6) { if (startingAddress < holdingRegsSize) { // check exception 2 ILLEGAL DATA ADDRESS unsigned int startingAddress = ((frame[2] << 8) | frame[3]); unsigned int regStatus = ((frame[4] << 8) | frame[5]); unsigned char responseFrameSize = 8; holdingRegs[startingAddress] = regStatus; crc16 = calculateCRC(responseFrameSize - 2); frame[responseFrameSize - 2] = crc16 >> 8; // split crc into 2 bytes frame[responseFrameSize - 1] = crc16 & 0xFF; sendPacket(responseFrameSize); } else exceptionResponse(2); // exception 2 ILLEGAL DATA ADDRESS } else if (function == 16) { // check if the recieved number of bytes matches the calculated bytes minus the request bytes // id + function + (2 * address bytes) + (2 * no of register bytes) + byte count + (2 * CRC bytes) = 9 bytes if (frame[6] == (buffer - 9)) { if (startingAddress < holdingRegsSize) { // check exception 2 ILLEGAL DATA ADDRESS if (maxData <= holdingRegsSize) { // check exception 3 ILLEGAL DATA VALUE address = 7; // start at the 8th byte in the frame for (index = startingAddress; index < maxData; index++) { holdingRegs[index] = ((frame[address] << 8) | frame[address + 1]); address += 2; } // only the first 6 bytes are used for CRC calculation crc16 = calculateCRC(6); frame[6] = crc16 >> 8; // split crc into 2 bytes frame[7] = crc16 & 0xFF; // a function 16 response is an echo of the first 6 bytes from the request + 2 crc bytes if (!broadcastFlag) // don't respond if it's a broadcast message sendPacket(8); } else exceptionResponse(3); // exception 3 ILLEGAL DATA VALUE } else exceptionResponse(2); // exception 2 ILLEGAL DATA ADDRESS } else errorCount++; // corrupted packet } else exceptionResponse(1); // exception 1 ILLEGAL FUNCTION } else // checksum failed errorCount++; } // incorrect id } else if (buffer > 0 && buffer < 8) errorCount++; // corrupted packet return errorCount; } void exceptionResponse(unsigned char exception) { errorCount++; // each call to exceptionResponse() will increment the errorCount if (!broadcastFlag) { // don't respond if its a broadcast message frame[0] = slaveID; frame[1] = (function | 0x80); // set the MSB bit high, informs the master of an exception frame[2] = exception; unsigned int crc16 = calculateCRC(3); // ID, function + 0x80, exception code == 3 bytes frame[3] = crc16 >> 8; frame[4] = crc16 & 0xFF; sendPacket(5); // exception response is always 5 bytes ID, function + 0x80, exception code, 2 bytes crc } } void modbus_configure(long baud, unsigned char _slaveID, unsigned char _TxEnablePin, unsigned int _holdingRegsSize, unsigned char _lowLatency) { slaveID = _slaveID; Serial.begin(baud); if (_TxEnablePin > 1) { // pin 0 & pin 1 are reserved for RX/TX. To disable set txenpin < 2 TxEnablePin = _TxEnablePin; pinMode(TxEnablePin, OUTPUT); digitalWrite(TxEnablePin, LOW); } // Modbus states that a baud rate higher than 19200 must use a fixed 750 us // for inter character time out and 1.75 ms for a frame delay. // For baud rates below 19200 the timeing is more critical and has to be calculated. // E.g. 9600 baud in a 10 bit packet is 960 characters per second // In milliseconds this will be 960characters per 1000ms. So for 1 character // 1000ms/960characters is 1.04167ms per character and finaly modbus states an // intercharacter must be 1.5T or 1.5 times longer than a normal character and thus // 1.5T = 1.04167ms * 1.5 = 1.5625ms. A frame delay is 3.5T. // Added experimental low latency delays. This makes the implementation // non-standard but practically it works with all major modbus master implementations. if (baud == 1000000 && _lowLatency) { T1_5 = 1; T3_5 = 10; } else if (baud >= 115200 && _lowLatency) { T1_5 = 75; T3_5 = 175; } else if (baud > 19200) { T1_5 = 750; T3_5 = 1750; } else { T1_5 = 15000000/baud; // 1T * 1.5 = T1.5 T3_5 = 35000000/baud; // 1T * 3.5 = T3.5 } holdingRegsSize = _holdingRegsSize; errorCount = 0; // initialize errorCount } unsigned int calculateCRC(byte bufferSize) { unsigned int temp, temp2, flag; temp = 0xFFFF; for (unsigned char i = 0; i < bufferSize; i++) { temp = temp ^ frame[i]; for (unsigned char j = 1; j <= 8; j++) { flag = temp & 0x0001; temp >>= 1; if (flag) temp ^= 0xA001; } } // Reverse byte order. temp2 = temp >> 8; temp = (temp << 8) | temp2; temp &= 0xFFFF; return temp; // the returned value is already swopped - crcLo byte is first & crcHi byte is last } void sendPacket(unsigned char bufferSize) { if (TxEnablePin > 1) digitalWrite(TxEnablePin, HIGH); for (unsigned char i = 0; i < bufferSize; i++) Serial.write(frame[i]); Serial.flush(); // allow a frame delay to indicate end of transmission delayMicroseconds(T3_5); if (TxEnablePin > 1) digitalWrite(TxEnablePin, LOW); } ================================================ FILE: SimpleModbusSlave/SimpleModbusSlave.h ================================================ #ifndef SIMPLE_MODBUS_SLAVE_H #define SIMPLE_MODBUS_SLAVE_H /* SimpleModbusSlave allows you to communicate to any slave using the Modbus RTU protocol. The crc calculation is based on the work published by jpmzometa at http://sites.google.com/site/jpmzometa/arduino-mbrt By Juan Bester : bester.juan@gmail.com The functions implemented are functions 3 and 16. read holding registers and preset multiple registers of the Modbus RTU Protocol, to be used over the Arduino serial connection. This implementation DOES NOT fully comply with the Modbus specifications. Specifically the frame time out have not been implemented according to Modbus standards. The code does however combine the check for inter character time out and frame time out by incorporating a maximum time out allowable when reading from the message stream. These library of functions are designed to enable a program send and receive data from a device that communicates using the Modbus protocol. SimpleModbusSlave implements an unsigned int return value on a call to modbus_update(). This value is the total error count since the slave started. It's useful for fault finding. This code is for a Modbus slave implementing functions 3 and 16 function 3: Reads the binary contents of holding registers (4X references) function 16: Presets values into a sequence of holding registers (4X references) All the functions share the same register array. Exception responses: 1 ILLEGAL FUNCTION 2 ILLEGAL DATA ADDRESS 3 ILLEGAL DATA VALUE Note: The Arduino serial ring buffer is 128 bytes or 64 registers. Most of the time you will connect the arduino to a master via serial using a MAX485 or similar. In a function 3 request the master will attempt to read from your slave and since 5 bytes is already used for ID, FUNCTION, NO OF BYTES and two BYTES CRC the master can only request 122 bytes or 61 registers. In a function 16 request the master will attempt to write to your slave and since a 9 bytes is already used for ID, FUNCTION, ADDRESS, NO OF REGISTERS, NO OF BYTES and two BYTES CRC the master can only write 118 bytes or 59 registers. Using the FTDI converter ic the maximum bytes you can send is limited to its internal buffer which is 60 bytes or 30 unsigned int registers. Thus: In a function 3 request the master will attempt to read from your slave and since 5 bytes is already used for ID, FUNCTION, NO OF BYTES and two BYTES CRC the master can only request 54 bytes or 27 registers. In a function 16 request the master will attempt to write to your slave and since a 9 bytes is already used for ID, FUNCTION, ADDRESS, NO OF REGISTERS, NO OF BYTES and two BYTES CRC the master can only write 50 bytes or 25 registers. Since it is assumed that you will mostly use the Arduino to connect to a master without using a USB to Serial converter the internal buffer is set the same as the Arduino Serial ring buffer which is 128 bytes. The functions included here have been derived from the Modbus Specifications and Implementation Guides http://www.modbus.org/docs/Modbus_over_serial_line_V1_02.pdf http://www.modbus.org/docs/Modbus_Application_Protocol_V1_1b.pdf http://www.modbus.org/docs/PI_MBUS_300.pdf */ #include "Arduino.h" // function definitions void modbus_configure(long baud, byte _slaveID, byte _TxEnablePin, unsigned int _holdingRegsSize, unsigned char _lowLatency); unsigned int modbus_update(unsigned int *holdingRegs); #endif ================================================ FILE: SimpleModbusSlave/examples/SimpleModbusSlaveExample/SimpleModbusSlaveExample.ino ================================================ #include #define ledPin 13 // onboard led #define buttonPin 7 // push button /* This example code has 9 holding registers. 6 analogue inputs, 1 button, 1 digital output and 1 register to indicate errors encountered since started. Function 5 (write single coil) is not implemented so I'm using a whole register and function 16 to set the onboard Led on the Atmega328P. The modbus_update() method updates the holdingRegs register array and checks communication. Note: The Arduino serial ring buffer is 128 bytes or 64 registers. Most of the time you will connect the arduino to a master via serial using a MAX485 or similar. In a function 3 request the master will attempt to read from your slave and since 5 bytes is already used for ID, FUNCTION, NO OF BYTES and two BYTES CRC the master can only request 122 bytes or 61 registers. In a function 16 request the master will attempt to write to your slave and since a 9 bytes is already used for ID, FUNCTION, ADDRESS, NO OF REGISTERS, NO OF BYTES and two BYTES CRC the master can only write 118 bytes or 59 registers. Using the FTDI USB to Serial converter the maximum bytes you can send is limited to its internal buffer which is 60 bytes or 30 unsigned int registers. Thus: In a function 3 request the master will attempt to read from your slave and since 5 bytes is already used for ID, FUNCTION, NO OF BYTES and two BYTES CRC the master can only request 54 bytes or 27 registers. In a function 16 request the master will attempt to write to your slave and since a 9 bytes is already used for ID, FUNCTION, ADDRESS, NO OF REGISTERS, NO OF BYTES and two BYTES CRC the master can only write 50 bytes or 25 registers. Since it is assumed that you will mostly use the Arduino to connect to a master without using a USB to Serial converter the internal buffer is set the same as the Arduino Serial ring buffer which is 128 bytes. */ // Using the enum instruction allows for an easy method for adding and // removing registers. Doing it this way saves you #defining the size // of your slaves register array each time you want to add more registers // and at a glimpse informs you of your slaves register layout. //////////////// registers of your slave /////////////////// enum { // just add or remove registers and you're good to go... // The first register starts at address 0 ADC0, ADC1, ADC2, ADC3, ADC4, ADC5, LED_STATE, BUTTON_STATE, TOTAL_ERRORS, // leave this one TOTAL_REGS_SIZE // total number of registers for function 3 and 16 share the same register array }; unsigned int holdingRegs[TOTAL_REGS_SIZE]; // function 3 and 16 register array //////////////////////////////////////////////////////////// void setup() { /* parameters(long baudrate, unsigned char ID, unsigned char transmit enable pin, unsigned int holding registers size, unsigned char low latency) The transmit enable pin is used in half duplex communication to activate a MAX485 or similar to deactivate this mode use any value < 2 because 0 & 1 is reserved for Rx & Tx. Low latency delays makes the implementation non-standard but practically it works with all major modbus master implementations. */ modbus_configure(115200, 2, 2, TOTAL_REGS_SIZE, 0); pinMode(ledPin, OUTPUT); pinMode(buttonPin, INPUT); } void loop() { // modbus_update() is the only method used in loop(). It returns the total error // count since the slave started. You don't have to use it but it's useful // for fault finding by the modbus master. holdingRegs[TOTAL_ERRORS] = modbus_update(holdingRegs); for (byte i = 0; i < 6; i++) { holdingRegs[i] = analogRead(i); delayMicroseconds(50); } byte buttonState = digitalRead(buttonPin); // read button states // assign the buttonState value to the holding register holdingRegs[BUTTON_STATE] = buttonState; // read the LED_STATE register value and set the onboard LED high or low with function 16 byte ledState = holdingRegs[LED_STATE]; if (ledState) // set led digitalWrite(ledPin, HIGH); if (ledState == 0) { // reset led digitalWrite(ledPin, LOW); } } ================================================ FILE: SimpleModbusSlave/keywords.txt ================================================ modbus_configure KEYWORD2 modbus_update KEYWORD2 ================================================ FILE: SimpleModbusSlaveSoftwareSerial/SimpleModbusSlaveSoftwareSerial.cpp ================================================ #include "SimpleModbusSlaveSoftwareSerial.h" #define BUFFER_SIZE 128 // frame[] is used to recieve and transmit packages. // The maximum serial ring buffer size is 128 unsigned char frame[BUFFER_SIZE]; unsigned int holdingRegsSize; // size of the register array unsigned char broadcastFlag; unsigned char slaveID; unsigned char function; unsigned char TxEnablePin; unsigned int errorCount; unsigned int T1_5; // inter character time out unsigned int T3_5; // frame delay SoftwareSerial* _port; // function definitions void exceptionResponse(unsigned char exception); unsigned int calculateCRC(unsigned char bufferSize); void sendPacket(unsigned char bufferSize); unsigned int modbus_update(unsigned int *holdingRegs) { unsigned char buffer = 0; unsigned char overflow = 0; while ((*_port).available()) { // The maximum number of bytes is limited to the serial buffer size of 128 bytes // If more bytes is received than the BUFFER_SIZE the overflow flag will be set and the // serial buffer will be red untill all the data is cleared from the receive buffer. if (overflow) (*_port).read(); else { if (buffer == BUFFER_SIZE) overflow = 1; frame[buffer] = (*_port).read(); buffer++; } delayMicroseconds(T1_5); // inter character time out } // If an overflow occurred increment the errorCount // variable and return to the main sketch without // responding to the request i.e. force a timeout if (overflow) return errorCount++; // The minimum request packet is 8 bytes for function 3 & 16 if (buffer > 6) { unsigned char id = frame[0]; broadcastFlag = 0; if (id == 0) broadcastFlag = 1; if (id == slaveID || broadcastFlag) { // if the recieved ID matches the slaveID or broadcasting id (0), continue unsigned int crc = ((frame[buffer - 2] << 8) | frame[buffer - 1]); // combine the crc Low & High bytes if (calculateCRC(buffer - 2) == crc) { // if the calculated crc matches the recieved crc continue function = frame[1]; unsigned int startingAddress = ((frame[2] << 8) | frame[3]); // combine the starting address bytes unsigned int no_of_registers = ((frame[4] << 8) | frame[5]); // combine the number of register bytes unsigned int maxData = startingAddress + no_of_registers; unsigned char index; unsigned char address; unsigned int crc16; // broadcasting is not supported for function 3 if (!broadcastFlag && (function == 3)) { if (startingAddress < holdingRegsSize) { // check exception 2 ILLEGAL DATA ADDRESS if (maxData <= holdingRegsSize) { // check exception 3 ILLEGAL DATA VALUE unsigned char noOfBytes = no_of_registers * 2; unsigned char responseFrameSize = 5 + noOfBytes; // ID, function, noOfBytes, (dataLo + dataHi) * number of registers, crcLo, crcHi frame[0] = slaveID; frame[1] = function; frame[2] = noOfBytes; address = 3; // PDU starts at the 4th byte unsigned int temp; for (index = startingAddress; index < maxData; index++) { temp = holdingRegs[index]; frame[address] = temp >> 8; // split the register into 2 bytes address++; frame[address] = temp & 0xFF; address++; } crc16 = calculateCRC(responseFrameSize - 2); frame[responseFrameSize - 2] = crc16 >> 8; // split crc into 2 bytes frame[responseFrameSize - 1] = crc16 & 0xFF; sendPacket(responseFrameSize); } else exceptionResponse(3); // exception 3 ILLEGAL DATA VALUE } else exceptionResponse(2); // exception 2 ILLEGAL DATA ADDRESS } else if (function == 6) { if (startingAddress < holdingRegsSize) { // check exception 2 ILLEGAL DATA ADDRESS unsigned int startingAddress = ((frame[2] << 8) | frame[3]); unsigned int regStatus = ((frame[4] << 8) | frame[5]); unsigned char responseFrameSize = 8; holdingRegs[startingAddress] = regStatus; crc16 = calculateCRC(responseFrameSize - 2); frame[responseFrameSize - 2] = crc16 >> 8; // split crc into 2 bytes frame[responseFrameSize - 1] = crc16 & 0xFF; sendPacket(responseFrameSize); } else exceptionResponse(2); // exception 2 ILLEGAL DATA ADDRESS } else if (function == 16) { // check if the recieved number of bytes matches the calculated bytes minus the request bytes // id + function + (2 * address bytes) + (2 * no of register bytes) + byte count + (2 * CRC bytes) = 9 bytes if (frame[6] == (buffer - 9)) { if (startingAddress < holdingRegsSize) { // check exception 2 ILLEGAL DATA ADDRESS if (maxData <= holdingRegsSize) { // check exception 3 ILLEGAL DATA VALUE address = 7; // start at the 8th byte in the frame for (index = startingAddress; index < maxData; index++) { holdingRegs[index] = ((frame[address] << 8) | frame[address + 1]); address += 2; } // only the first 6 bytes are used for CRC calculation crc16 = calculateCRC(6); frame[6] = crc16 >> 8; // split crc into 2 bytes frame[7] = crc16 & 0xFF; // a function 16 response is an echo of the first 6 bytes from the request + 2 crc bytes if (!broadcastFlag) // don't respond if it's a broadcast message sendPacket(8); } else exceptionResponse(3); // exception 3 ILLEGAL DATA VALUE } else exceptionResponse(2); // exception 2 ILLEGAL DATA ADDRESS } else errorCount++; // corrupted packet } else exceptionResponse(1); // exception 1 ILLEGAL FUNCTION } else // checksum failed errorCount++; } // incorrect id } else if (buffer > 0 && buffer < 8) errorCount++; // corrupted packet return errorCount; } void exceptionResponse(unsigned char exception) { errorCount++; // each call to exceptionResponse() will increment the errorCount if (!broadcastFlag) { // don't respond if its a broadcast message frame[0] = slaveID; frame[1] = (function | 0x80); // set the MSB bit high, informs the master of an exception frame[2] = exception; unsigned int crc16 = calculateCRC(3); // ID, function + 0x80, exception code == 3 bytes frame[3] = crc16 >> 8; frame[4] = crc16 & 0xFF; sendPacket(5); // exception response is always 5 bytes ID, function + 0x80, exception code, 2 bytes crc } } void modbus_configure(SoftwareSerial* comPort, long baud, unsigned char _slaveID, unsigned char _TxEnablePin, unsigned int _holdingRegsSize) { _port = comPort; slaveID = _slaveID; (*_port).begin(baud); if (_TxEnablePin > 1) { // pin 0 & pin 1 are reserved for RX/TX. To disable set txenpin < 2 TxEnablePin = _TxEnablePin; pinMode(TxEnablePin, OUTPUT); digitalWrite(TxEnablePin, LOW); } // Modbus states that a baud rate higher than 19200 must use a fixed 750 us // for inter character time out and 1.75 ms for a frame delay. // For baud rates below 19200 the timeing is more critical and has to be calculated. // E.g. 9600 baud in a 10 bit packet is 960 characters per second // In milliseconds this will be 960characters per 1000ms. So for 1 character // 1000ms/960characters is 1.04167ms per character and finaly modbus states an // intercharacter must be 1.5T or 1.5 times longer than a normal character and thus // 1.5T = 1.04167ms * 1.5 = 1.5625ms. A frame delay is 3.5T. if (baud > 19200) { T1_5 = 150; T3_5 = 350; } else { T1_5 = 15000000/baud; // 1T * 1.5 = T1.5 T3_5 = 35000000/baud; // 1T * 3.5 = T3.5 } holdingRegsSize = _holdingRegsSize; errorCount = 0; // initialize errorCount } unsigned int calculateCRC(byte bufferSize) { unsigned int temp, temp2, flag; temp = 0xFFFF; for (unsigned char i = 0; i < bufferSize; i++) { temp = temp ^ frame[i]; for (unsigned char j = 1; j <= 8; j++) { flag = temp & 0x0001; temp >>= 1; if (flag) temp ^= 0xA001; } } // Reverse byte order. temp2 = temp >> 8; temp = (temp << 8) | temp2; temp &= 0xFFFF; return temp; // the returned value is already swopped - crcLo byte is first & crcHi byte is last } void sendPacket(unsigned char bufferSize) { if (TxEnablePin > 1) digitalWrite(TxEnablePin, HIGH); for (unsigned char i = 0; i < bufferSize; i++) (*_port).write(frame[i]); (*_port).flush(); // allow a frame delay to indicate end of transmission delayMicroseconds(T3_5); if (TxEnablePin > 1) digitalWrite(TxEnablePin, LOW); } ================================================ FILE: SimpleModbusSlaveSoftwareSerial/SimpleModbusSlaveSoftwareSerial.h ================================================ #ifndef SIMPLE_MODBUS_SLAVE_H #define SIMPLE_MODBUS_SLAVE_H /* SimpleModbusSlave allows you to communicate to any slave using the Modbus RTU protocol. The crc calculation is based on the work published by jpmzometa at http://sites.google.com/site/jpmzometa/arduino-mbrt By Juan Bester : bester.juan@gmail.com The functions implemented are functions 3 and 16. read holding registers and preset multiple registers of the Modbus RTU Protocol, to be used over the Arduino serial connection. This implementation DOES NOT fully comply with the Modbus specifications. Specifically the frame time out have not been implemented according to Modbus standards. The code does however combine the check for inter character time out and frame time out by incorporating a maximum time out allowable when reading from the message stream. These library of functions are designed to enable a program send and receive data from a device that communicates using the Modbus protocol. SimpleModbusSlave implements an unsigned int return value on a call to modbus_update(). This value is the total error count since the slave started. It's useful for fault finding. This code is for a Modbus slave implementing functions 3 and 16 function 3: Reads the binary contents of holding registers (4X references) function 16: Presets values into a sequence of holding registers (4X references) All the functions share the same register array. Exception responses: 1 ILLEGAL FUNCTION 2 ILLEGAL DATA ADDRESS 3 ILLEGAL DATA VALUE Note: The Arduino serial ring buffer is 128 bytes or 64 registers. Most of the time you will connect the arduino to a master via serial using a MAX485 or similar. In a function 3 request the master will attempt to read from your slave and since 5 bytes is already used for ID, FUNCTION, NO OF BYTES and two BYTES CRC the master can only request 122 bytes or 61 registers. In a function 16 request the master will attempt to write to your slave and since a 9 bytes is already used for ID, FUNCTION, ADDRESS, NO OF REGISTERS, NO OF BYTES and two BYTES CRC the master can only write 118 bytes or 59 registers. Using the FTDI converter ic the maximum bytes you can send is limited to its internal buffer which is 60 bytes or 30 unsigned int registers. Thus: In a function 3 request the master will attempt to read from your slave and since 5 bytes is already used for ID, FUNCTION, NO OF BYTES and two BYTES CRC the master can only request 54 bytes or 27 registers. In a function 16 request the master will attempt to write to your slave and since a 9 bytes is already used for ID, FUNCTION, ADDRESS, NO OF REGISTERS, NO OF BYTES and two BYTES CRC the master can only write 50 bytes or 25 registers. Since it is assumed that you will mostly use the Arduino to connect to a master without using a USB to Serial converter the internal buffer is set the same as the Arduino Serial ring buffer which is 128 bytes. The functions included here have been derived from the Modbus Specifications and Implementation Guides http://www.modbus.org/docs/Modbus_over_serial_line_V1_02.pdf http://www.modbus.org/docs/Modbus_Application_Protocol_V1_1b.pdf http://www.modbus.org/docs/PI_MBUS_300.pdf */ #include "Arduino.h" #include "SoftwareSerial.h" // function definitions void modbus_configure(SoftwareSerial* comPort, long baud, unsigned char _slaveID, unsigned char _TxEnablePin, unsigned int _holdingRegsSize); unsigned int modbus_update(unsigned int *holdingRegs); #endif ================================================ FILE: SimpleModbusSlaveSoftwareSerial/examples/SimpleModbusTinyExample/SimpleModbusTinyExample.ino ================================================ #include #include #define buttonPin0 2 // push button #define buttonPin1 3 // push button /* This example code has 2 holding registers. 2 buttons, and 1 register to indicate errors encountered since started. The modbus_update() method updates the holdingRegs register array and checks communication. Note: The Arduino serial ring buffer is 128 bytes or 64 registers. Most of the time you will connect the arduino to a master via serial using a MAX485 or similar. In a function 3 request the master will attempt to read from your slave and since 5 bytes is already used for ID, FUNCTION, NO OF BYTES and two BYTES CRC the master can only request 122 bytes or 61 registers. In a function 16 request the master will attempt to write to your slave and since a 9 bytes is already used for ID, FUNCTION, ADDRESS, NO OF REGISTERS, NO OF BYTES and two BYTES CRC the master can only write 118 bytes or 59 registers. Using the FTDI USB to Serial converter the maximum bytes you can send is limited to its internal buffer which is 60 bytes or 30 unsigned int registers. Thus: In a function 3 request the master will attempt to read from your slave and since 5 bytes is already used for ID, FUNCTION, NO OF BYTES and two BYTES CRC the master can only request 54 bytes or 27 registers. In a function 16 request the master will attempt to write to your slave and since a 9 bytes is already used for ID, FUNCTION, ADDRESS, NO OF REGISTERS, NO OF BYTES and two BYTES CRC the master can only write 50 bytes or 25 registers. Since it is assumed that you will mostly use the Arduino to connect to a master without using a USB to Serial converter the internal buffer is set the same as the Arduino Serial ring buffer which is 128 bytes. */ // Using the enum instruction allows for an easy method for adding and // removing registers. Doing it this way saves you #defining the size // of your slaves register array each time you want to add more registers // and at a glimpse informs you of your slaves register layout. //////////////// registers of your slave /////////////////// enum { // just add or remove registers and your good to go... // The first register starts at address 0 BUTTON0, BUTTON1, TOTAL_ERRORS, // leave this one TOTAL_REGS_SIZE // total number of registers for function 3 and 16 share the same register array }; unsigned int holdingRegs[TOTAL_REGS_SIZE]; // function 3 and 16 register array //////////////////////////////////////////////////////////// #define RX 0 // Arduino defined pin (PB0, package pin #5) #define TX 1 // Arduino defined pin (PB1, package pin #6) #define RS485_EN 2 // pin to set transmission mode on RS485 chip (PB2, package pin #7) #define BAUD_RATE 115200 // baud rate for serial communication #define deviceID 3 // this device address SoftwareSerial mySerial(RX, TX); void setup() { /* parameters( SoftwareSerial* comPort long baudrate, unsigned char ID, unsigned char transmit enable pin, unsigned int holding registers size) The transmit enable pin is used in half duplex communication to activate a MAX485 or similar to deactivate this mode use any value < 2 because 0 & 1 is reserved for Rx & Tx */ modbus_configure(&mySerial, BAUD_RATE, deviceID, RS485_EN, TOTAL_REGS_SIZE); pinMode(buttonPin0, INPUT); pinMode(buttonPin1, INPUT); } void loop() { // modbus_update() is the only method used in loop(). It returns the total error // count since the slave started. You don't have to use it but it's useful // for fault finding by the modbus master. holdingRegs[TOTAL_ERRORS] = modbus_update(holdingRegs); holdingRegs[BUTTON0] = analogRead(buttonPin0); delayMicroseconds(50); holdingRegs[BUTTON1] = analogRead(buttonPin1); delayMicroseconds(50); } ================================================ FILE: SimpleModbusSlaveSoftwareSerial/keywords.txt ================================================ modbus_configure KEYWORD2 modbus_update KEYWORD2 ================================================ FILE: gpl-3.0.txt ================================================ GNU GENERAL PUBLIC LICENSE Version 3, 29 June 2007 Copyright (C) 2007 Free Software Foundation, Inc. Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Preamble The GNU General Public License is a free, copyleft license for software and other kinds of works. 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All other non-permissive additional terms are considered "further restrictions" within the meaning of section 10. If the Program as you received it, or any part of it, contains a notice stating that it is governed by this License along with a term that is a further restriction, you may remove that term. If a license document contains a further restriction but permits relicensing or conveying under this License, you may add to a covered work material governed by the terms of that license document, provided that the further restriction does not survive such relicensing or conveying. If you add terms to a covered work in accord with this section, you must place, in the relevant source files, a statement of the additional terms that apply to those files, or a notice indicating where to find the applicable terms. Additional terms, permissive or non-permissive, may be stated in the form of a separately written license, or stated as exceptions; the above requirements apply either way. 8. Termination. You may not propagate or modify a covered work except as expressly provided under this License. Any attempt otherwise to propagate or modify it is void, and will automatically terminate your rights under this License (including any patent licenses granted under the third paragraph of section 11). However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation. Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice. Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, you do not qualify to receive new licenses for the same material under section 10. 9. Acceptance Not Required for Having Copies. You are not required to accept this License in order to receive or run a copy of the Program. Ancillary propagation of a covered work occurring solely as a consequence of using peer-to-peer transmission to receive a copy likewise does not require acceptance. However, nothing other than this License grants you permission to propagate or modify any covered work. These actions infringe copyright if you do not accept this License. Therefore, by modifying or propagating a covered work, you indicate your acceptance of this License to do so. 10. Automatic Licensing of Downstream Recipients. Each time you convey a covered work, the recipient automatically receives a license from the original licensors, to run, modify and propagate that work, subject to this License. You are not responsible for enforcing compliance by third parties with this License. An "entity transaction" is a transaction transferring control of an organization, or substantially all assets of one, or subdividing an organization, or merging organizations. If propagation of a covered work results from an entity transaction, each party to that transaction who receives a copy of the work also receives whatever licenses to the work the party's predecessor in interest had or could give under the previous paragraph, plus a right to possession of the Corresponding Source of the work from the predecessor in interest, if the predecessor has it or can get it with reasonable efforts. You may not impose any further restrictions on the exercise of the rights granted or affirmed under this License. For example, you may not impose a license fee, royalty, or other charge for exercise of rights granted under this License, and you may not initiate litigation (including a cross-claim or counterclaim in a lawsuit) alleging that any patent claim is infringed by making, using, selling, offering for sale, or importing the Program or any portion of it. 11. Patents. A "contributor" is a copyright holder who authorizes use under this License of the Program or a work on which the Program is based. The work thus licensed is called the contributor's "contributor version". A contributor's "essential patent claims" are all patent claims owned or controlled by the contributor, whether already acquired or hereafter acquired, that would be infringed by some manner, permitted by this License, of making, using, or selling its contributor version, but do not include claims that would be infringed only as a consequence of further modification of the contributor version. For purposes of this definition, "control" includes the right to grant patent sublicenses in a manner consistent with the requirements of this License. Each contributor grants you a non-exclusive, worldwide, royalty-free patent license under the contributor's essential patent claims, to make, use, sell, offer for sale, import and otherwise run, modify and propagate the contents of its contributor version. In the following three paragraphs, a "patent license" is any express agreement or commitment, however denominated, not to enforce a patent (such as an express permission to practice a patent or covenant not to sue for patent infringement). To "grant" such a patent license to a party means to make such an agreement or commitment not to enforce a patent against the party. If you convey a covered work, knowingly relying on a patent license, and the Corresponding Source of the work is not available for anyone to copy, free of charge and under the terms of this License, through a publicly available network server or other readily accessible means, then you must either (1) cause the Corresponding Source to be so available, or (2) arrange to deprive yourself of the benefit of the patent license for this particular work, or (3) arrange, in a manner consistent with the requirements of this License, to extend the patent license to downstream recipients. "Knowingly relying" means you have actual knowledge that, but for the patent license, your conveying the covered work in a country, or your recipient's use of the covered work in a country, would infringe one or more identifiable patents in that country that you have reason to believe are valid. If, pursuant to or in connection with a single transaction or arrangement, you convey, or propagate by procuring conveyance of, a covered work, and grant a patent license to some of the parties receiving the covered work authorizing them to use, propagate, modify or convey a specific copy of the covered work, then the patent license you grant is automatically extended to all recipients of the covered work and works based on it. A patent license is "discriminatory" if it does not include within the scope of its coverage, prohibits the exercise of, or is conditioned on the non-exercise of one or more of the rights that are specifically granted under this License. You may not convey a covered work if you are a party to an arrangement with a third party that is in the business of distributing software, under which you make payment to the third party based on the extent of your activity of conveying the work, and under which the third party grants, to any of the parties who would receive the covered work from you, a discriminatory patent license (a) in connection with copies of the covered work conveyed by you (or copies made from those copies), or (b) primarily for and in connection with specific products or compilations that contain the covered work, unless you entered into that arrangement, or that patent license was granted, prior to 28 March 2007. Nothing in this License shall be construed as excluding or limiting any implied license or other defenses to infringement that may otherwise be available to you under applicable patent law. 12. No Surrender of Others' Freedom. If conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot convey a covered work so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not convey it at all. For example, if you agree to terms that obligate you to collect a royalty for further conveying from those to whom you convey the Program, the only way you could satisfy both those terms and this License would be to refrain entirely from conveying the Program. 13. Use with the GNU Affero General Public License. Notwithstanding any other provision of this License, you have permission to link or combine any covered work with a work licensed under version 3 of the GNU Affero General Public License into a single combined work, and to convey the resulting work. The terms of this License will continue to apply to the part which is the covered work, but the special requirements of the GNU Affero General Public License, section 13, concerning interaction through a network will apply to the combination as such. 14. Revised Versions of this License. The Free Software Foundation may publish revised and/or new versions of the GNU General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. Each version is given a distinguishing version number. If the Program specifies that a certain numbered version of the GNU General Public License "or any later version" applies to it, you have the option of following the terms and conditions either of that numbered version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of the GNU General Public License, you may choose any version ever published by the Free Software Foundation. If the Program specifies that a proxy can decide which future versions of the GNU General Public License can be used, that proxy's public statement of acceptance of a version permanently authorizes you to choose that version for the Program. Later license versions may give you additional or different permissions. However, no additional obligations are imposed on any author or copyright holder as a result of your choosing to follow a later version. 15. Disclaimer of Warranty. THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 16. Limitation of Liability. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. 17. Interpretation of Sections 15 and 16. If the disclaimer of warranty and limitation of liability provided above cannot be given local legal effect according to their terms, reviewing courts shall apply local law that most closely approximates an absolute waiver of all civil liability in connection with the Program, unless a warranty or assumption of liability accompanies a copy of the Program in return for a fee. END OF TERMS AND CONDITIONS How to Apply These Terms to Your New Programs If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms. To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively state the exclusion of warranty; and each file should have at least the "copyright" line and a pointer to where the full notice is found. Copyright (C) This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . Also add information on how to contact you by electronic and paper mail. If the program does terminal interaction, make it output a short notice like this when it starts in an interactive mode: Copyright (C) This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. This is free software, and you are welcome to redistribute it under certain conditions; type `show c' for details. The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, your program's commands might be different; for a GUI interface, you would use an "about box". You should also get your employer (if you work as a programmer) or school, if any, to sign a "copyright disclaimer" for the program, if necessary. For more information on this, and how to apply and follow the GNU GPL, see . The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License. But first, please read .