focal (3) modbus_new_tcp_pi.3.gz

Provided by: libmodbus-dev_3.1.6-2_amd64 bug

NAME
       modbus_new_tcp_pi - create a libmodbus context for TCP Protocol Independent


SYNOPSIS
       modbus_t *modbus_new_tcp_pi(const char *node, const char *service);


DESCRIPTION
       The modbus_new_tcp_pi() function shall allocate and initialize a modbus_t structure to communicate with a
       Modbus TCP IPv4 or IPv6 server.

       The node argument specifies the host name or IP address of the host to connect to, eg. "192.168.0.5" ,
       "::1" or "server.com". A NULL value can be used to listen any addresses in server mode.

       The service argument is the service name/port number to connect to. To use the default Modbus port use
       the string "502". On many Unix systems, it’s convenient to use a port number greater than or equal to
       1024 because it’s not necessary to have administrator privileges.


RETURN VALUE
       The function shall return a pointer to a modbus_t structure if successful. Otherwise it shall return NULL
       and set errno to one of the values defined below.


ERRORS
       EINVAL
           The node string is empty or has been truncated. The service string is empty or has been truncated.

       ENOMEM
           Out of memory. Possibly, the application hits its memory limit and/or whole system is running out of
           memory.


EXAMPLE
           modbus_t *ctx;

           ctx = modbus_new_tcp_pi("::1", "1502");
           if (ctx == NULL) {
               fprintf(stderr, "Unable to allocate libmodbus context\n");
               return -1;
           }

           if (modbus_connect(ctx) == -1) {
               fprintf(stderr, "Connection failed: %s\n", modbus_strerror(errno));
               modbus_free(ctx);
               return -1;
           }


SEE ALSO
       modbus_new_tcp(3) modbus_tcp_pi_listen(3) modbus_free(3)


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