// =================================================================================================
// eModbus: Copyright 2020 by Michael Harwerth, Bert Melis and the contributors to eModbus
// MIT license - see license.md for details
// =================================================================================================
#include "options.h"
#if HAS_FREERTOS || HAS_RP2040_FREERTOS
#include "ModbusMessage.h"
#include "RTUutils.h"
#undef LOCAL_LOG_LEVEL
// #define LOCAL_LOG_LEVEL LOG_LEVEL_VERBOSE
#include "Logging.h"
// CRC16 pre-calculated tables
static constexpr 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
};
static constexpr 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
};
// calcCRC: calculate Modbus CRC16 on a given array of bytes
uint16_t RTUutils::calcCRC(const uint8_t *data, uint16_t len) {
uint8_t crcHi = 0xFF;
uint8_t crcLo = 0xFF;
while (len--) {
uint8_t index = crcLo ^ *data++;
crcLo = crcHi ^ crcHiTable[index];
crcHi = crcLoTable[index];
}
return (crcHi > 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;
} else {
// Give some slack
delay(1);
}
}
}
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]