picmodbus's Introduction

PICmodbus PIC-CCS code

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