modbus_set_socket - Man Page

int modbus_set_socket(modbus_t *ctx, int s);

The modbus_set_socket() function shall set the socket or file descriptor in the libmodbus context. This function is useful for managing multiple client connections to the same server.

The function shall return 0 if successful. Otherwise it shall return -1 and set errno.

ctx = modbus_new_tcp("127.0.0.1", 1502);
server_socket = modbus_tcp_listen(ctx, NB_CONNECTION);

FD_ZERO(&rdset);
FD_SET(server_socket, &rdset);

/* .... */

if (FD_ISSET(master_socket, &rdset)) {
    modbus_set_socket(ctx, master_socket);
    rc = modbus_receive(ctx, query);
    if (rc != -1) {
        modbus_reply(ctx, query, rc, mb_mapping);
    }
}

modbus_get_socket(3)

The libmodbus documentation was written by Stéphane Raimbault <stephane.raimbault@gmail.com>

libmodbus(7), modbus_get_socket(3), modbus_receive(3).