// ================================================================================================= // eModbus: Copyright 2020 by Michael Harwerth, Bert Melis and the contributors to eModbus // MIT license - see license.md for details // ================================================================================================= #include "options.h" #include "ModbusMessage.h" #include "RTUutils.h" #undef LOCAL_LOG_LEVEL // #define LOCAL_LOG_LEVEL LOG_LEVEL_VERBOSE #include "Logging.h" // calcCRC: calculate Modbus CRC16 on a given array of bytes uint16_t RTUutils::calcCRC(const uint8_t *data, uint16_t len) { // CRC16 pre-calculated tables const uint8_t crcHiTable[] = { 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40 }; const uint8_t crcLoTable[] = { 0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06, 0x07, 0xC7, 0x05, 0xC5, 0xC4, 0x04, 0xCC, 0x0C, 0x0D, 0xCD, 0x0F, 0xCF, 0xCE, 0x0E, 0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09, 0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9, 0x1B, 0xDB, 0xDA, 0x1A, 0x1E, 0xDE, 0xDF, 0x1F, 0xDD, 0x1D, 0x1C, 0xDC, 0x14, 0xD4, 0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3, 0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3, 0xF2, 0x32, 0x36, 0xF6, 0xF7, 0x37, 0xF5, 0x35, 0x34, 0xF4, 0x3C, 0xFC, 0xFD, 0x3D, 0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A, 0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38, 0x28, 0xE8, 0xE9, 0x29, 0xEB, 0x2B, 0x2A, 0xEA, 0xEE, 0x2E, 0x2F, 0xEF, 0x2D, 0xED, 0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26, 0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60, 0x61, 0xA1, 0x63, 0xA3, 0xA2, 0x62, 0x66, 0xA6, 0xA7, 0x67, 0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F, 0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68, 0x78, 0xB8, 0xB9, 0x79, 0xBB, 0x7B, 0x7A, 0xBA, 0xBE, 0x7E, 0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5, 0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71, 0x70, 0xB0, 0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92, 0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C, 0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B, 0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89, 0x4B, 0x8B, 0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C, 0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42, 0x43, 0x83, 0x41, 0x81, 0x80, 0x40 }; uint8_t crcHi = 0xFF; uint8_t crcLo = 0xFF; uint8_t index; while (len--) { index = crcLo ^ *data++; crcLo = crcHi ^ crcHiTable[index]; crcHi = crcLoTable[index]; } return (crcHi << 8 | crcLo); } // calcCRC: calculate Modbus CRC16 on a given message uint16_t RTUutils::calcCRC(ModbusMessage msg) { return calcCRC(msg.data(), msg.size()); } // validCRC #1: check the given CRC in a block of data for correctness bool RTUutils::validCRC(const uint8_t *data, uint16_t len) { return validCRC(data, len - 2, data[len - 2] | (data[len - 1] << 8)); } // validCRC #2: check the CRC of a block of data against a given one for equality bool RTUutils::validCRC(const uint8_t *data, uint16_t len, uint16_t CRC) { uint16_t crc16 = calcCRC(data, len); if (CRC == crc16) return true; return false; } // validCRC #3: check the given CRC in a message for correctness bool RTUutils::validCRC(ModbusMessage msg) { return validCRC(msg.data(), msg.size() - 2, msg[msg.size() - 2] | (msg[msg.size() - 1] << 8)); } // validCRC #4: check the CRC of a message against a given one for equality bool RTUutils::validCRC(ModbusMessage msg, uint16_t CRC) { return validCRC(msg.data(), msg.size(), CRC); } // addCRC: calculate the CRC for a given RTUMessage and add it to the end void RTUutils::addCRC(ModbusMessage& raw) { uint16_t crc16 = calcCRC(raw.data(), raw.size()); raw.push_back(crc16 & 0xff); raw.push_back((crc16 >> 8) & 0xFF); } // calculateInterval: determine the minimal gap time between messages uint32_t RTUutils::calculateInterval(uint32_t baudRate) { uint32_t interval = 0; // silent interval is at least 3.5x character time interval = 35000000UL / baudRate; // 3.5 * 10 bits * 1000 µs * 1000 ms / baud if (interval < 1750) interval = 1750; // lower limit according to Modbus RTU standard LOG_V("Calc interval(%u)=%u\n", baudRate, interval); return interval; } // send: send a message via Serial, watching interval times - including CRC! void RTUutils::send(Stream& serial, unsigned long& lastMicros, uint32_t interval, RTScallback rts, const uint8_t *data, uint16_t len, bool ASCIImode) { // Clear serial buffers while (serial.available()) serial.read(); // Treat ASCII differently if (ASCIImode) { // Toggle rtsPin, if necessary rts(HIGH); // Yes, ASCII mode. Send lead-in serial.write(':'); uint16_t cnt = len; uint8_t crc = 0; uint8_t *cp = (uint8_t *)data; // Loop over all bytes of the message while (cnt--) { // Write two nibbles as ASCII characters serial.write(ASCIIwrite[(*cp >> 4) & 0x0F]); serial.write(ASCIIwrite[*cp & 0x0F]); // Advance CRC crc += *cp; // Next byte cp++; } // Finalize CRC (2's complement) crc = ~crc; crc++; // Write ist - two nibbles as ASCII characters serial.write(ASCIIwrite[(crc >> 4) & 0x0F]); serial.write(ASCIIwrite[crc & 0x0F]); // Send lead-out serial.write("\r\n"); serial.flush(); // Toggle rtsPin, if necessary rts(LOW); } else { // RTU mode uint16_t crc16 = calcCRC(data, len); // Respect interval - we must not toggle rtsPin before if (micros() - lastMicros < interval) delayMicroseconds(interval - (micros() - lastMicros)); // Toggle rtsPin, if necessary rts(HIGH); // Write message serial.write(data, len); // Write CRC in LSB order serial.write(crc16 & 0xff); serial.write((crc16 >> 8) & 0xFF); serial.flush(); // Toggle rtsPin, if necessary rts(LOW); } HEXDUMP_D("Sent packet", data, len); // Mark end-of-message time for next interval lastMicros = micros(); } // send: send a message via Serial, watching interval times - including CRC! void RTUutils::send(Stream& serial, unsigned long& lastMicros, uint32_t interval, RTScallback rts, ModbusMessage raw, bool ASCIImode) { send(serial, lastMicros, interval, rts, raw.data(), raw.size(), ASCIImode); } // receive: get (any) message from Serial, taking care of timeout and interval ModbusMessage RTUutils::receive(uint8_t caller, Stream& serial, uint32_t timeout, unsigned long& lastMicros, uint32_t interval, bool ASCIImode, bool skipLeadingZeroBytes) { // Allocate initial receive buffer size: 1 block of BUFBLOCKSIZE bytes const uint16_t BUFBLOCKSIZE(512); uint8_t *buffer = new uint8_t[BUFBLOCKSIZE]; ModbusMessage rv; // Index into buffer uint16_t bufferPtr = 0; // Byte read int b = 0; // State machine states, RTU mode enum STATES : uint8_t { WAIT_DATA = 0, IN_PACKET, DATA_READ, FINISHED }; // State machine states, ASCII mode enum ASTATES : uint8_t { A_WAIT_DATA = 0, A_DATA, A_WAIT_LEAD_OUT, A_FINISHED }; uint8_t state; // Timeout tracker unsigned long TimeOut = millis(); // RTU mode? if (!ASCIImode) { // Yes. state = WAIT_DATA; // interval tracker lastMicros = micros(); while (state != FINISHED) { switch (state) { // WAIT_DATA: await first data byte, but watch timeout case WAIT_DATA: // Blindly try to read a byte b = serial.read(); // Did we get one? if (b >= 0) { // Yes. Note the time. lastMicros = micros(); // Do we need to skip it, if it is zero? if (b > 0 || !skipLeadingZeroBytes) { // No, we can go process it regularly buffer[bufferPtr++] = b; state = IN_PACKET; } } else { // No, we had no byte. Just check the timeout period if (millis() - TimeOut >= timeout) { rv.push_back(TIMEOUT); state = FINISHED; } delay(1); } break; // IN_PACKET: read data until a gap of at least _interval time passed without another byte arriving case IN_PACKET: // tight loop until finished reading or error while (state == IN_PACKET) { // Is there a byte? while (serial.available()) { // Yes, collect it buffer[bufferPtr++] = serial.read(); // Mark time of last byte lastMicros = micros(); // Buffer full? if (bufferPtr >= BUFBLOCKSIZE) { // Yes. Something fishy here - bail out! rv.push_back(PACKET_LENGTH_ERROR); state = FINISHED; break; } } // No more byte read if (state == IN_PACKET) { // Are we past the interval gap? if (micros() - lastMicros >= interval) { // Yes, terminate reading LOG_V("%c/%ldus without data after %u\n", (const char)caller, micros() - lastMicros, bufferPtr); state = DATA_READ; break; } } } break; // DATA_READ: successfully gathered some data. Prepare return object. case DATA_READ: // Did we get a sensible buffer length? LOG_V("%c/", (const char)caller); HEXDUMP_V("Raw buffer received", buffer, bufferPtr); if (bufferPtr >= 4) { // Yes. Check CRC if (!validCRC(buffer, bufferPtr)) { // Ooops. CRC is wrong. rv.push_back(CRC_ERROR); } else { // CRC was fine, Now allocate response object without the CRC for (uint16_t i = 0; i < bufferPtr - 2; ++i) { rv.push_back(buffer[i]); } } } else { // No, packet was too short for anything usable. Return error rv.push_back(PACKET_LENGTH_ERROR); } state = FINISHED; break; // FINISHED: we are done, clean up. case FINISHED: // CLear serial buffer in case something is left trailing // May happen with servers too slow! while (serial.available()) serial.read(); break; } } } else { // We are in ASCII mode. state = A_WAIT_DATA; // Track nibbles in a byte bool byteComplete = true; // Track bytes read bool hadBytes = false; // ASCII crc byte uint8_t crc = 0; while (state != A_FINISHED) { // Always watch timeout - 1s if (millis() - TimeOut >= timeout) { // Timeout! Bail out with error rv.push_back(TIMEOUT); state = A_FINISHED; } else { // Still in time. Check for another byte on serial if (!hadBytes && serial.available()) { b = serial.read(); if (b >= 0) { hadBytes = true; } } // Only use state machine with new data arrived if (hadBytes) { // First reset timeout TimeOut = millis(); // Is it a valid character? if ((b & 0x80) || ASCIIread[b] == 0xFF) { // No. Report error and leave. rv.clear(); rv.push_back(ASCII_INVALID_CHAR); hadBytes = false; state = A_FINISHED; } else { // Yes, is valid. Furtheron use interpreted byte b = ASCIIread[b]; switch (state) { // A_WAIT_DATA: await lead-in byte ':' case A_WAIT_DATA: // Is it the lead-in? if (b == 0xF0) { // Yes, proceed to data read state state = A_DATA; } // byte was consumed in any case hadBytes = false; break; // A_DATA: read data as it comes case A_DATA: // Lead-out byte 1 received? if (b == 0xF1) { // Yes. Was last buffer byte completed? if (byteComplete) { // Yes. Move to final state state = A_WAIT_LEAD_OUT; } else { // No, signal with error rv.push_back(PACKET_LENGTH_ERROR); state = A_FINISHED; } } else { // No lead-out, must be data byte. // Is it valid? if (b < 0xF0) { // Yes. Add it into current buffer byte buffer[bufferPtr] <<= 4; buffer[bufferPtr] += (b & 0x0F); // Advance nibble byteComplete = !byteComplete; // Was it the second of the byte? if (byteComplete) { // Yes. Advance CRC and move buffer pointer by one crc += buffer[bufferPtr]; bufferPtr++; buffer[bufferPtr] = 0; } } else { // No, garbage. report error rv.push_back(ASCII_INVALID_CHAR); state = A_FINISHED; } } hadBytes = false; break; // A_WAIT_LEAD_OUT: await \n case A_WAIT_LEAD_OUT: if (b == 0xF2) { // Lead-out byte 2 received. Transfer buffer to returned message LOG_V("%c/", (const char)caller); HEXDUMP_V("Raw buffer received", buffer, bufferPtr); // Did we get a sensible buffer length? if (bufferPtr >= 3) { // Yes. Was the CRC calculated correctly? if (crc == 0) { // Yes, reduce buffer by 1 to get rid of CRC byte... bufferPtr--; // Move data into returned message for (uint16_t i = 0; i < bufferPtr; ++i) { rv.push_back(buffer[i]); } } else { // No, CRC calculation seems to have failed rv.push_back(ASCII_CRC_ERR); } } else { // No, packet was too short for anything usable. Return error rv.push_back(PACKET_LENGTH_ERROR); } } else { // No lead out byte 2, but something else - report error. rv.push_back(ASCII_FRAME_ERR); } state = A_FINISHED; break; // A_FINISHED: Message completed case A_FINISHED: // Clean up serial buffer while (serial.available()) serial.read(); break; } } } else { // No data received, so give the task scheduler room to breathe delay(1); } } } } // Deallocate buffer delete[] buffer; LOG_D("%c/", (const char)caller); HEXDUMP_D("Received packet", rv.data(), rv.size()); return rv; } // Lower 7 bit ASCII characters - all invalid are set to 0xFF const char RTUutils::ASCIIread[] = { /* 00-07 */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 08-0F */ 0xFF, 0xFF, 0xF2, 0xFF, 0xFF, 0xF1, 0xFF, 0xFF, // LF + CR /* 10-17 */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 18-1F */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 20-27 */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 28-2F */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 30-37 */ 0, 1, 2, 3, 4, 5, 6, 7, // digits 0-7 /* 38-3F */ 8, 9, 0xF0, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // digits 8 + 9, : /* 40-47 */ 0xFF, 10, 11, 12, 13, 14, 15, 0xFF, // digits A-F /* 48-4F */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 50-57 */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 58-5F */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 60-67 */ 0xFF, 10, 11, 12, 13, 14, 15, 0xFF, // digits a-f /* 68-6F */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 70-77 */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 78-7F */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF }; // Writable ASCII chars for hex digits const char RTUutils::ASCIIwrite[] = { 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46 };