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>