| MODBUS_TCP_LISTEN(3) | libmodbus Manual | MODBUS_TCP_LISTEN(3) |
modbus_tcp_listen - create and listen a TCP Modbus socket (IPv4)
int modbus_tcp_listen(modbus_t *ctx, int nb_connection);
The modbus_tcp_listen() function shall create a socket and listen to maximum nb_connection incoming connections on the specified IP address. The context _ctx _must be allocated and initialized with modbus_new_tcp(3) before to set the IP address to listen, if IP address is set to NULL, any addresses will be listen.
The function shall return a new socket if successful. Otherwise it shall return -1 and set errno.
For detailed examples, see source files in tests directory:
...
/* To listen any addresses on port 502 */
ctx = modbus_new_tcp(NULL, 502);
/* Handle until 10 established connections */
server_socket = modbus_tcp_listen(ctx, 10);
/* Clear the reference set of socket */
FD_ZERO(&refset);
/* Add the server socket */
FD_SET(server_socket, &refset);
if (select(server_socket + 1, &refset, NULL, NULL, NULL) == -1) {
}
...
close(server_socket);
modbus_free(ctx);
modbus_new_tcp(3) modbus_tcp_accept(3) modbus_tcp_pi_listen(3)
The libmodbus documentation was written by Stéphane Raimbault <stephane.raimbault@gmail.com>
| 11/20/2021 | libmodbus v3.1.4 |