SYNOPSIS

int modbus_tcp_pi_listen(modbus_t *ctx, int nb_connection);

DESCRIPTION

The modbus_tcp_pi_listen() function shall create a socket and listen to maximum nb_connection incoming connections on the specified nodes. The context ctx must be allocated and initialized with modbus_new_tcp_pi(3) before to set the node to listen, if node 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:

  • unit-test-server.c, simple but handle only one connection 

...

ctx = modbus_new_tcp_pi("::0", "502");
s = modbus_tcp_pi_listen(ctx, 1);
modbus_tcp_pi_accept(ctx, &s);

for (;;) {
    rc = modbus_receive(ctx, query);
    modbus_replay(ctx, query, rc, mb_mapping);
}
...

mclose(s);
modbus_free(ctx);

  • bandwidth-server-many-up.c, handles several connections at once

SEE ALSO

modbus_new_tcp_pi(3) modbus_tcp_pi_accept(3) modbus_tcp_listen(3)

AUTHORS

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