bionic (3) modbus_new_tcp_pi.3.gz

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.

       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 modbus_new_tcp_pi() 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.

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_new_rtu(3) modbus_free(3)

AUTHORS

       The libmodbus documentation was written by Stéphane Raimbault <stephane.raimbault@gmail.com[1]>

NOTES

        1. stephane.raimbault@gmail.com
           mailto:stephane.raimbault@gmail.com