modbus_tcp_listen - Man Page

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(3) 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

modbus_new_tcp(3) modbus_tcp_accept(3) modbus_tcp_pi_listen(3)

Authors

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

Referenced By

modbus_new_tcp(3), modbus_tcp_accept(3), modbus_tcp_pi_accept(3), modbus_tcp_pi_listen(3).

01/25/2024 libmodbus v3.1.7 libmodbus Manual