UDP OPEN statement

Purpose

Create a socket for an application to communicate with a UDP server or client using the UDP (connectionless) protocol over Winsock (UDP/IP).

Syntax

UDP OPEN [PORT p&] AS [#] fNum& [TIMEOUT timeoutval&]

Remarks

Open a UDP socket (port or service) for UDP communication.  FNum& is a file number such as #1, or a variable with a value obtained using the FREEFILE function.

PORT

If PORT p& is specified, the socket is opened as a server that can receive UDP data.  Use the UDP NOTIFY statement to receive server notifications from the socket so that the data can be retrieved.  Common port numbers include 7 (Echo, see RFC862); 37 (Time, see RFC868); and 123 (NTP - RFC1305).

TIMEOUT

The TIMEOUT option allows you to specify how long, in milliseconds (mSec), a UDP SEND/RECV operation should wait for completion.  If the specified number of milliseconds elapses, the UDP operation will fail, and the ERR system variable will be set to indicate a run-time Error 24 ("Device timeout").  The default timeout is 60000 milliseconds (60 seconds).

See also

TCP and UDP Communication, FREEFILE, TCP OPEN, UDP CLOSE, UDP NOTIFY, UDP RECV, UDP SEND