Modbus libmodbus simple test

main.cpp

#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <modbus/modbus.h>

#include <iostream>
#include <cstdio>
#include <cstdlib>


int main()
{

    int tabRegSize = 32;
    uint16_t tabReg[tabRegSize];
    uint8_t inputReg[tabRegSize];

    memset(tabReg, 0, sizeof(tabReg));
    memset(inputReg, 0, sizeof(inputReg));

    modbus_t* ctx = modbus_new_tcp("127.0.0.1", 1502);
    //modbus_t* ctx = modbus_new_tcp("192.168.0.221", 502);
    if(modbus_connect(ctx) == -1)
    {
        std::cout << "Error while connecting to ModBus" << std::endl;
    }
    modbus_set_debug(ctx, TRUE);
    modbus_set_slave(ctx, 0);

    // Read 5 registers from the address 0
    int numOfRegistersRead = modbus_read_registers(ctx, 0, 5, tabReg);
    //int numOfRegistersRead = modbus_read_input_bits(ctx, 0, 5, inputReg);
    if(numOfRegistersRead < 0)
    {
        std::cout << "Error on read: " << modbus_strerror(errno) << std::endl;
    }

    for(int i = 0; i < numOfRegistersRead; i++)
    {
        //std::cout << "[" << (int)i << "] " << (int)inputReg[i] << std::endl;
        std::cout << "[" << (int)i << "] " << (int)tabReg[i] << std::endl;
    }
    
    modbus_write_registers(ctx, 5, 10, tabReg);

    modbus_close(ctx);
    modbus_free(ctx);
}

Makefile

all:
	g++ main.cpp -lmodbus