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| MODBUS_TCP_LISTEN(3) | libmodbus Manual | MODBUS_TCP_LISTEN(3) |
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(3) before to set the IP address to listen, if IP address is set to NULL, 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:•unit-test-server.c, simple but handle only one
connection
•bandwidth-server-many-up.c, handles several
connections at once
...
/* 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>| 12/19/2018 | libmodbus v3.1.4 |