NAME

       modbus_new_tcp - create a libmodbus context for TCP/IPv4

SYNOPSIS

       modbus_t *modbus_new_tcp(const char *ip, int port);

DESCRIPTION

       The modbus_new_tcp() function shall allocate and initialize a modbus_t structure to
       communicate with a Modbus TCP/IPv4 server.

       The ip argument specifies the IP address of the server to which the client wants etablish
       a connection.

       The port argument is the TCP port to use. Set the port to MODBUS_TCP_DEFAULT_PORT to use
       the default one (502). 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() 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
           An invalid IP address was given.

EXAMPLE

           modbus_t *ctx;

           ctx = modbus_new_tcp("127.0.0.1", 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_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