120 lines
3.3 KiB
C
120 lines
3.3 KiB
C
/*!
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* @file modbus.c
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* @authors Simon Donnet-Monay & Remi Heredero
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* @date 14 march 2023
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* @biref
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*/
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#include "modbus.h"
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#include "crc.h"
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// Modbus functions
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#define READ_INPUT_REGISTERS 0x04 //!< Modbus function for read input register = 04
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#define READ_HOLDING_REGISTERS 0x03 //!< Modbus function for read holding register = 03
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#define WRITE_SINGLE_REGISTER 0x06 //!< Modbus function for write a single register = 06
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// Modbus data model
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uint8_t modbusAddress;
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uint16_t input_registers[2];
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uint16_t holding_registers[2];
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// Modbus error codes
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#define ILLEGAL_FUNCTION 1
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#define ILLEGAL_DATA_ADDRESS 2
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#define ILLEGAL_DATA_VALUE 3
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#define SLAVE_DEVICE_FAILURE 4
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/**
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* Buffers for serial receive and send operations
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* which are more than one byte long
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**/
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uint8_t rx_buf[256];
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uint8_t tx_buf[256];
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// Current position pointer for storing receive position
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uint8_t recPtr = 0;
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void modbus_timer(void) {
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INTCONbits.TMR0IF = 0;
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recPtr = 0;
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TMR0_StopTimer();
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modbus_analyse_and_answer();
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}
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extern uint16_t measure_voltage();
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uint8_t modbus_analyse_and_answer(void) {
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// TODO -> complete the modbus analyse and answer
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uint16_t length = 0;
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if(rx_buf[0] == modbusAddress){
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tx_buf[0] = rx_buf[0]; // Adress
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tx_buf[1] = rx_buf[1]; // Function
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uint16_t adresseRegister = ((uint16_t)rx_buf[2] << 8) | rx_buf[3];
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switch(rx_buf[1]){ // Check the function from rx buffer
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case READ_INPUT_REGISTERS:
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length = ((uint16_t)rx_buf[4] << 8) | rx_buf[5];
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tx_buf[2] = (uint8_t)(length*2); // Data length
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for(uint16_t i = 0; i < length; i++){ // Data
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tx_buf[i*2+4] = input_registers[adresseRegister+i];
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tx_buf[i*2+3] = (input_registers[adresseRegister+i] >> 8);
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}
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length*=2;
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length+=3;
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break;
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case READ_HOLDING_REGISTERS:
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length = ((uint16_t)rx_buf[4] << 8) | rx_buf[5];
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tx_buf[2] = (uint8_t)(length*2); // Data length
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for(uint16_t i = 0; i < length; i++){ // Data
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tx_buf[i*2+4] = holding_registers[adresseRegister+i];
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tx_buf[i*2+3] = (holding_registers[adresseRegister+i] >> 8);
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}
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length*=2;
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length+=3;
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break;
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case WRITE_SINGLE_REGISTER:
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holding_registers[adresseRegister] = ((uint16_t)rx_buf[4] << 8) | rx_buf[5];
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for (int i = 2; i <= 5; i++) {
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tx_buf[i] = rx_buf[i];
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length = i+1;
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}
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break;
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}
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}
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rx_buf[0] = 0;
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modbus_send(length);
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}
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void modbus_char_recvd(void)
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{
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rx_buf[recPtr++] = RCREG1;
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TMR0_Reload();
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TMR0_StartTimer();
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}
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void modbus_send(uint8_t length)
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{
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uint16_t crc = CRC16(tx_buf, length);
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tx_buf[length] = crc;
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tx_buf[length+1] = crc >> 8;
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length += 2; // add 2 CRC bytes for total size
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// For all the bytes to be transmitted
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for (uint8_t i = 0; i < length; i++){
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EUSART1_Write(tx_buf[i]);
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}
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}
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void modbus_init(uint8_t address)
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{
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modbusAddress = address;
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holding_registers[1] = address;
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EUSART1_SetRxInterruptHandler(modbus_char_recvd);
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TMR0_SetInterruptHandler(modbus_timer);
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}
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