[FIXED] undefined reference to modbus_new_tcp Eclipse

Issue

I'm very new to C/C++ and trying to connect to modbus. I am using Eclipse with the following code:

#include <stdio.h>
#include <stdlib.h>
#include <modbus/modbus.h>

int main(void) {
    modbus_t *mb = modbus_new_tcp("10.84.4.128", "502");
    puts("!!!Hello World!!!"); /* prints !!!Hello World!!! */
    return EXIT_SUCCESS;
}

I get the error: src/Modbus.c:17: undefined reference to 'modbus_new_tcp'

In Eclipse I've when to properties and added /usr/include/modbus to the Library search path (-L) but still get the above error.

How do I define the reference?

Solution

Don't use #include <modbus.h> directly. Instead, include modbus_asc.h or modbus_rtu.h or modbus_tcp.h. This file modbus.h will be included automatically

Answered By - Shri
Answer Checked By - Gilberto Lyons (JavaFixing Admin)