PIC Microcontroller Master and Slave Modbus RTU Protocol
ISIS Proteus file [https://github.com/worrajak/PICmodbus/blob/master/ModBus.DSN]
1.Modbus master
PIC18F458 configuration
#include <18f458.h>
#fuses HS, NOWDT
#use delay(clock=20M)
#define MODBUS_TYPE MODBUS_TYPE_MASTER
#define MODBUS_SERIAL_TYPE MODBUS_RTU //use MODBUS_ASCII for ASCII mode
#define MODBUS_SERIAL_RX_BUFFER_SIZE 64
SDM120 or modbus BuadRate to 2400bps
#define MODBUS_SERIAL_BAUD 2400
using EXT INT RB0 (PIC18F458)
#define MODBUS_SERIAL_INT_SOURCE MODBUS_INT_EXT
and config pin
#define MODBUS_SERIAL_TX_PIN PIN_B1 // Data transmit pin
#define MODBUS_SERIAL_RX_PIN PIN_B0 // Data receive pin
#define MODBUS_SERIAL_ENABLE_PIN PIN_B2 // Controls DE pin for RS485
#define MODBUS_SERIAL_RX_ENABLE 0 // Controls RE pin for RS485
- Slave modbus PIC16F690
#include <16F690.h>
#DEVICE *=16 ADC=10
#fuses NOPROTECT,INTRC,NOWDT,PUT,NOBROWNOUT,MCLR
#use delay(clock=4M)
#define MODBUS_TYPE MODBUS_TYPE_SLAVE
#define MODBUS_SERIAL_TYPE MODBUS_RTU //use MODBUS_ASCII for ASCII mode
#define MODBUS_SERIAL_RX_BUFFER_SIZE 64
#define MODBUS_SERIAL_BAUD 2400
using EXT INT RDA (UART) (PIC18F458)
#define MODBUS_SERIAL_INT_SOURCE MODBUS_INT_RDA
and config pin
#define MODBUS_SERIAL_TX_PIN PIN_B7 // Data transmit pin
#define MODBUS_SERIAL_RX_PIN PIN_B5 // Data receive pin
#define MODBUS_SERIAL_ENABLE_PIN PIN_B4 // Controls DE pin for RS485
#define MODBUS_SERIAL_RX_ENABLE 0 // Controls RE pin for RS485
