Modbus Protocol
ajit.nayak87
Posts: 76
Dear all.
I have the c++ code for Arduino Uno modbus protocol. can someone help me to convert the code c ++ to c.
I have the c++ code for Arduino Uno modbus protocol. can someone help me to convert the code c ++ to c.
void Modbus::get_FC3() {
uint8_t u8byte, i;
u8byte = 3;
for (i = 0; i < au8Buffer[ 2 ] / 2; i++) {
au16regs[ i ] = word(
au8Buffer[ u8byte ],
au8Buffer[ u8byte + 1 ]);
u8byte += 2;
}
}
int8_t Modbus::process_FC1( uint16_t *regs, uint8_t u8size ) {
uint8_t u8currentRegister, u8currentBit, u8bytesno, u8bitsno;
uint8_t u8CopyBufferSize;
uint16_t u16currentCoil, u16coil;
// get the first and last coil from the message
uint16_t u16StartCoil = word( au8Buffer[ ADD_HI ], au8Buffer[ ADD_LO ] );
uint16_t u16Coilno = word( au8Buffer[ NB_HI ], au8Buffer[ NB_LO ] );
// put the number of bytes in the outcoming message
u8bytesno = (uint8_t) (u16Coilno / 8);
if (u16Coilno % 8 != 0) u8bytesno ++;
au8Buffer[ ADD_HI ] = u8bytesno;
u8BufferSize = ADD_LO;
// read each coil from the register map and put its value inside the outcoming message
u8bitsno = 0;
for (u16currentCoil = 0; u16currentCoil < u16Coilno; u16currentCoil++) {
u16coil = u16StartCoil + u16currentCoil;
u8currentRegister = (uint8_t) (u16coil / 16);
u8currentBit = (uint8_t) (u16coil % 16);
bitWrite(
au8Buffer[ u8BufferSize ],
u8bitsno,
bitRead( regs[ u8currentRegister ], u8currentBit ) );
u8bitsno ++;
if (u8bitsno > 7) {
u8bitsno = 0;
u8BufferSize++;
}
}
// send outcoming message
if (u16Coilno % 8 != 0) u8BufferSize ++;
u8CopyBufferSize = u8BufferSize +2;
sendTxBuffer();
return u8CopyBufferSize;
}
int8_t Modbus::process_FC3( uint16_t *regs, uint8_t u8size ) {
uint8_t u8StartAdd = word( au8Buffer[ ADD_HI ], au8Buffer[ ADD_LO ] );
uint8_t u8regsno = word( au8Buffer[ NB_HI ], au8Buffer[ NB_LO ] );
uint8_t u8CopyBufferSize;
uint8_t i;
au8Buffer[ 2 ] = u8regsno * 2;
u8BufferSize = 3;
for (i = u8StartAdd; i < u8StartAdd + u8regsno; i++) {
au8Buffer[ u8BufferSize ] = highByte(regs[i]);
u8BufferSize++;
au8Buffer[ u8BufferSize ] = lowByte(regs[i]);
u8BufferSize++;
}
u8CopyBufferSize = u8BufferSize +2;
sendTxBuffer();
return u8CopyBufferSize;
}
int8_t Modbus::process_FC5( uint16_t *regs, uint8_t u8size ) {
uint8_t u8currentRegister, u8currentBit;
uint8_t u8CopyBufferSize;
uint16_t u16coil = word( au8Buffer[ ADD_HI ], au8Buffer[ ADD_LO ] );
// point to the register and its bit
u8currentRegister = (uint8_t) (u16coil / 16);
u8currentBit = (uint8_t) (u16coil % 16);
// write to coil
bitWrite(
regs[ u8currentRegister ],
u8currentBit,
au8Buffer[ NB_HI ] == 0xff );
// send answer to master
u8BufferSize = 6;
u8CopyBufferSize = u8BufferSize +2;
sendTxBuffer();
return u8CopyBufferSize;
}
int8_t Modbus::process_FC6( uint16_t *regs, uint8_t u8size ) {
uint8_t u8add = word( au8Buffer[ ADD_HI ], au8Buffer[ ADD_LO ] );
uint8_t u8CopyBufferSize;
uint16_t u16val = word( au8Buffer[ NB_HI ], au8Buffer[ NB_LO ] );
regs[ u8add ] = u16val;
// keep the same header
u8BufferSize = RESPONSE_SIZE;
u8CopyBufferSize = u8BufferSize +2;
sendTxBuffer();
return u8CopyBufferSize;
}
int8_t Modbus::process_FC15( uint16_t *regs, uint8_t u8size ) {
uint8_t u8currentRegister, u8currentBit, u8frameByte, u8bitsno;
uint8_t u8CopyBufferSize;
uint16_t u16currentCoil, u16coil;
boolean bTemp;
// get the first and last coil from the message
uint16_t u16StartCoil = word( au8Buffer[ ADD_HI ], au8Buffer[ ADD_LO ] );
uint16_t u16Coilno = word( au8Buffer[ NB_HI ], au8Buffer[ NB_LO ] );
// read each coil from the register map and put its value inside the outcoming message
u8bitsno = 0;
u8frameByte = 7;
for (u16currentCoil = 0; u16currentCoil < u16Coilno; u16currentCoil++) {
u16coil = u16StartCoil + u16currentCoil;
u8currentRegister = (uint8_t) (u16coil / 16);
u8currentBit = (uint8_t) (u16coil % 16);
bTemp = bitRead(
au8Buffer[ u8frameByte ],
u8bitsno );
bitWrite(
regs[ u8currentRegister ],
u8currentBit,
bTemp );
u8bitsno ++;
if (u8bitsno > 7) {
u8bitsno = 0;
u8frameByte++;
}
}
// send outcoming message
// it's just a copy of the incomping frame until 6th byte
u8BufferSize = 6;
u8CopyBufferSize = u8BufferSize +2;
sendTxBuffer();
return u8CopyBufferSize;
}
int8_t Modbus::process_FC16( uint16_t *regs, uint8_t u8size ) {
uint8_t u8func = au8Buffer[ FUNC ]; // get the original FUNC code
uint8_t u8StartAdd = au8Buffer[ ADD_HI ] << 8 | au8Buffer[ ADD_LO ];
uint8_t u8regsno = au8Buffer[ NB_HI ] << 8 | au8Buffer[ NB_LO ];
uint8_t u8CopyBufferSize;
uint8_t i;
uint16_t temp;
// build header
au8Buffer[ NB_HI ] = 0;
au8Buffer[ NB_LO ] = u8regsno;
u8BufferSize = RESPONSE_SIZE;
// write registers
for (i = 0; i < u8regsno; i++) {
temp = word(
au8Buffer[ (BYTE_CNT + 1) + i * 2 ],
au8Buffer[ (BYTE_CNT + 2) + i * 2 ]);
regs[ u8StartAdd + i ] = temp;
}
u8CopyBufferSize = u8BufferSize +2;
sendTxBuffer();
return u8CopyBufferSize;
}
Comments
[code] int8_t Modbus::query( modbus_t telegram ) { uint8_t u8regsno, u8bytesno; if (u8id != 0) return -2; if (u8state != COM_IDLE) return -1; if ((telegram.u8id == 0) || (telegram.u8id > 247)) return -3; au16regs = telegram.au16reg; // telegram header au8Buffer[ ID ] = telegram.u8id; au8Buffer[ FUNC ] = telegram.u8fct; au8Buffer[ ADD_HI ] = highByte(telegram.u16RegAdd ); au8Buffer[ ADD_LO ] = lowByte( telegram.u16RegAdd ); switch ( telegram.u8fct ) { case MB_FC_READ_COILS: case MB_FC_READ_DISCRETE_INPUT: case MB_FC_READ_REGISTERS: case MB_FC_READ_INPUT_REGISTER: au8Buffer[ NB_HI ] = highByte(telegram.u16CoilsNo ); au8Buffer[ NB_LO ] = lowByte( telegram.u16CoilsNo ); u8BufferSize = 6; break; case MB_FC_WRITE_COIL: au8Buffer[ NB_HI ] = ((au16regs[0] > 0) ? 0xff : 0); au8Buffer[ NB_LO ] = 0; u8BufferSize = 6; break; case MB_FC_WRITE_REGISTER: au8Buffer[ NB_HI ] = highByte(au16regs[0]); au8Buffer[ NB_LO ] = lowByte(au16regs[0]); u8BufferSize = 6; break; case MB_FC_WRITE_MULTIPLE_COILS: u8regsno = telegram.u16CoilsNo / 16; u8bytesno = u8regsno * 2; if ((telegram.u16CoilsNo % 16) != 0) { u8bytesno++; u8regsno++; } au8Buffer[ NB_HI ] = highByte(telegram.u16CoilsNo ); au8Buffer[ NB_LO ] = lowByte( telegram.u16CoilsNo ); au8Buffer[ NB_LO + 1 ] = u8bytesno; u8BufferSize = 7; u8regsno = u8bytesno = 0; // now auxiliary registers for (uint16_t i = 0; i < telegram.u16CoilsNo; i++) { } break; case MB_FC_WRITE_MULTIPLE_REGISTERS: au8Buffer[ NB_HI ] = highByte(telegram.u16CoilsNo ); au8Buffer[ NB_LO ] = lowByte( telegram.u16CoilsNo ); au8Buffer[ NB_LO + 1 ] = (uint8_t) ( telegram.u16CoilsNo * 2 ); u8BufferSize = 7; for (uint16_t i = 0; i < telegram.u16CoilsNo; i++) { au8Buffer[ u8BufferSize ] = highByte( au16regs[ i ] ); u8BufferSize++; au8Buffer[ u8BufferSize ] = lowByte( au16regs[ i ] ); u8BufferSize++; } break; } sendTxBuffer(); u8state = COM_WAITING; return 0; } int8_t Modbus::poll() { // check if there is any incoming frame uint8_t u8current = port->available(); if (millis() > u32timeOut) { u8state = COM_IDLE; u16errCnt++; return 0; } if (u8current == 0) return 0; // check T35 after frame end or still no frame end if (u8current != u8lastRec) { u8lastRec = u8current; u32time = millis() + T35; return 0; } if (millis() < u32time) return 0; // transfer Serial buffer frame to auBuffer u8lastRec = 0; int8_t i8state = getRxBuffer(); if (i8state < 7) { u8state = COM_IDLE; u16errCnt++; return i8state; } // validate message: id, CRC, FCT, exception uint8_t u8exception = validateAnswer(); if (u8exception != 0) { u8state = COM_IDLE; return u8exception; } // process answer switch ( au8Buffer[ FUNC ] ) { case MB_FC_READ_COILS: case MB_FC_READ_DISCRETE_INPUT: // call get_FC1 to transfer the incoming message to au16regs buffer // get_FC1( ); break; case MB_FC_READ_INPUT_REGISTER: case MB_FC_READ_REGISTERS : // call get_FC3 to transfer the incoming message to au16regs buffer get_FC3( ); break; case MB_FC_WRITE_COIL: case MB_FC_WRITE_REGISTER : case MB_FC_WRITE_MULTIPLE_COILS: case MB_FC_WRITE_MULTIPLE_REGISTERS : // nothing to do break; default: break; } u8state = COM_IDLE; return u8BufferSize; } int8_t Modbus::poll( uint16_t *regs, uint8_t u8size ) { au16regs = regs; u8regsize = u8size; // check if there is any incoming frame uint8_t u8current = port->available(); if (u8current == 0) return 0; // check T35 after frame end or still no frame end if (u8current != u8lastRec) { u8lastRec = u8current; u32time = millis() + T35; return 0; } if (millis() < u32time) return 0; u8lastRec = 0; int8_t i8state = getRxBuffer(); if (i8state < 7) return i8state; // check slave id if (au8Buffer[ ID ] != u8id) return 0; // validate message: CRC, FCT, address and size uint8_t u8exception = validateRequest(); if (u8exception > 0) { if (u8exception != NO_REPLY) { buildException( u8exception ); sendTxBuffer(); } return u8exception; } u32timeOut = millis() + long(u16timeOut); // process message switch ( au8Buffer[ FUNC ] ) { case MB_FC_READ_COILS: case MB_FC_READ_DISCRETE_INPUT: return process_FC1( regs, u8size ); break; case MB_FC_READ_INPUT_REGISTER: case MB_FC_READ_REGISTERS : return process_FC3( regs, u8size ); break; case MB_FC_WRITE_COIL: return process_FC5( regs, u8size ); break; case MB_FC_WRITE_REGISTER : return process_FC6( regs, u8size ); break; case MB_FC_WRITE_MULTIPLE_COILS: return process_FC15( regs, u8size ); break; case MB_FC_WRITE_MULTIPLE_REGISTERS : return process_FC16( regs, u8size ); break; default: break; } } void Modbus::init(uint8_t u8id, uint8_t u8serno, uint8_t u8txenpin) { this->u8id = u8id; this->u8serno = (u8serno > 3) ? 0 : u8serno; this->u8txenpin = u8txenpin; this->u16timeOut = 1000;// intially set for 1000 } int8_t Modbus::getRxBuffer() { boolean bBuffOverflow = false; if (u8txenpin > 1) digitalWrite( u8txenpin, LOW ); u8BufferSize = 0; while ( port->available() ) { au8Buffer[ u8BufferSize ] = port->read(); u8BufferSize ++; if (u8BufferSize >= MAX_BUFFER) bBuffOverflow = true; } u16InCnt++; if (bBuffOverflow) { u16errCnt++; return ERR_BUFF_OVERFLOW; } u32timeOut=500; // u32timeOut = millis() + (unsigned long) u16timeOut; return u8BufferSize; } void Modbus::sendTxBuffer() { uint8_t i = 0; // append CRC to message uint16_t u16crc = calcCRC( u8BufferSize ); au8Buffer[ u8BufferSize ] = u16crc >> 8; u8BufferSize++; au8Buffer[ u8BufferSize ] = u16crc & 0x00ff; u8BufferSize++; // set RS485 transceiver to transmit mode if (u8txenpin > 1) { switch ( u8serno ) { #if defined(UBRR1H) case 1: UCSR1A = UCSR1A | (1 << TXC1); break; #endif #if defined(UBRR2H) case 2: UCSR2A = UCSR2A | (1 << TXC2); break; #endif #if defined(UBRR3H) case 3: UCSR3A = UCSR3A | (1 << TXC3); break; #endif case 0: default: UCSR0A = UCSR0A | (1 << TXC0); break; } digitalWrite( u8txenpin, HIGH ); } // transfer buffer to serial line port->write( au8Buffer, u8BufferSize ); // keep RS485 transceiver in transmit mode as long as sending if (u8txenpin > 1) { switch ( u8serno ) { #if defined(UBRR1H) case 1: while (!(UCSR1A & (1 << TXC1))); break; #endif #if defined(UBRR2H) case 2: while (!(UCSR2A & (1 << TXC2))); break; #endif #if defined(UBRR3H) case 3: while (!(UCSR3A & (1 << TXC3))); break; #endif case 0: default: while (!(UCSR0A & (1 << TXC0))); break; } // return RS485 transceiver to receive mode digitalWrite( u8txenpin, LOW ); } port->flush(); u8BufferSize = 0; // set time-out for master // u32timeOut = millis() + (unsigned long) u16timeOut; u32timeOut=500; // increase message counter u16OutCnt++; } uint16_t Modbus::calcCRC(uint8_t u8length) { unsigned int temp, temp2, flag; temp = 0xFFFF; for (unsigned char i = 0; i < u8length; i++) { temp = temp ^ au8Buffer[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; // the returned value is already swapped // crcLo byte is first & crcHi byte is last return temp; } uint8_t Modbus::validateRequest() { // check message crc vs calculated crc uint16_t u16MsgCRC = ((au8Buffer[u8BufferSize - 2] << 8) | au8Buffer[u8BufferSize - 1]); // combine the crc Low & High bytes if ( calcCRC( u8BufferSize - 2 ) != u16MsgCRC ) { u16errCnt ++; return NO_REPLY; } // check fct code boolean isSupported = false; for (uint8_t i = 0; i < sizeof( fctsupported ); i++) { if (fctsupported[i] == au8Buffer[FUNC]) { isSupported = 1; break; } } if (!isSupported) { u16errCnt ++; return EXC_FUNC_CODE; } // check start address & nb range // uint16_t u16regs = 4000; uint16_t u16regs = 0; uint8_t u8regs; switch ( au8Buffer[ FUNC ] ) { case MB_FC_READ_COILS: case MB_FC_READ_DISCRETE_INPUT: case MB_FC_WRITE_MULTIPLE_COILS: u16regs = word( au8Buffer[ ADD_HI ], au8Buffer[ ADD_LO ]) / 16; u16regs += word( au8Buffer[ NB_HI ], au8Buffer[ NB_LO ]) / 16; u8regs = (uint8_t) u16regs; if (u8regs > u8regsize) return EXC_ADDR_RANGE; break; case MB_FC_WRITE_COIL: u16regs = word( au8Buffer[ ADD_HI ], au8Buffer[ ADD_LO ]) / 16; u8regs = (uint8_t) u16regs; if (u8regs > u8regsize) return EXC_ADDR_RANGE; break; case MB_FC_WRITE_REGISTER : u16regs = word( au8Buffer[ ADD_HI ], au8Buffer[ ADD_LO ]); u8regs = (uint8_t) u16regs; if (u8regs > u8regsize) return EXC_ADDR_RANGE; break; case MB_FC_READ_REGISTERS : case MB_FC_READ_INPUT_REGISTER : case MB_FC_WRITE_MULTIPLE_REGISTERS : u16regs = word( au8Buffer[ ADD_HI ], au8Buffer[ ADD_LO ]); u16regs += word( au8Buffer[ NB_HI ], au8Buffer[ NB_LO ]); u8regs = (uint8_t) u16regs; if (u8regs > u8regsize) return EXC_ADDR_RANGE; break; } return 0; // OK, no exception code thrown } uint8_t Modbus::validateAnswer() { // check message crc vs calculated crc uint16_t u16MsgCRC = ((au8Buffer[u8BufferSize - 2] << 8) | au8Buffer[u8BufferSize - 1]); // combine the crc Low & High bytes if ( calcCRC( u8BufferSize - 2 ) != u16MsgCRC ) { u16errCnt ++; return NO_REPLY; } // check exception if ((au8Buffer[ FUNC ] & 0x80) != 0) { u16errCnt ++; return ERR_EXCEPTION; } // check fct code boolean isSupported = false; for (uint8_t i = 0; i < sizeof( fctsupported ); i++) { if (fctsupported[i] == au8Buffer[FUNC]) { isSupported = 1; break; } } if (!isSupported) { u16errCnt ++; return EXC_FUNC_CODE; } return 0; // OK, no exception code thrown } void Modbus::buildException( uint8_t u8exception ) { uint8_t u8func = au8Buffer[ FUNC ]; // get the original FUNC code au8Buffer[ ID ] = u8id; au8Buffer[ FUNC ] = u8func + 0x80; au8Buffer[ 2 ] = u8exception; u8BufferSize = EXCEPTION_SIZE; }[/code]