Name

modbus_tcp_listen - create and listen a TCP Modbus socket (IPv4)

Synopsis

int modbus_tcp_listen(modbus_t *ctx, int nb_connection);

Description

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⟩ before to set the IP address to listen, if IP address is set to NULL or '0.0.0.0', any addresses will be listen.

Return value

The function shall return a new socket if successful. Otherwise it shall return -1 and set errno.

Example

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);

See also