Cicode Programming Reference > Cicode Function Categories > Tag Functions Introduction > TagEventQueue


Opens the tag update event queue. The I/O server writes events into this queue as they are processed. These events include tag updates from drivers that support time-stamped data.

To read events from this queue, use the QueRead() or QuePeek() functions. The data put into the queue contains the following fields:

To use this function, you need to enable the tag update event queue with the [IOServer]EnableEventQueue parameter. This parameter will tell the I/O Server to start placing events into the queue. The function TagEventFormat() returns a handle to the format of the data placed into the string field.

Enabling this formatting feature can increase CPU loading and reduce performance of the I/O Server as every tag update event is formatted and placed in the queue. You should reconsider using this feature if a decrease in performance is noticeable.

The maximum length of each queue is controlled by the [Code]Queue parameter. You may need to adjust this parameter so as not to miss alarm events. When the queue is full, the I/O Server will discard events.



Parameters - None

Return Value

The queue handle of the Tag Update Event queue.

Related Functions

QuePeek, QueRead, TagEventFormat


   INT status;
   INT queue;
   INT format;
   INT eventId;
   STRING event;
   INT sec;
   INT ms;
   TIMESTAMP time;
   queue = TagEventQueue();
   format = TagEventFormat();
	IF (queue <> -1 AND format <> -1) THEN
	WHILE (true) DO
	 status = QueRead(queue, eventId, event, 1);
	 IF status = 0 THEN
		 ErrLog("eventId: " + IntToStr(eventId));
		 StrToFmt(format, event);
		 ErrLog("   driver: " + FmtGetField(format, "Driver"));
		 ErrLog("   port: " + FmtGetField(format, "Port"));
		 ErrLog("   unit: " + FmtGetField(format, "Unit"));
		 ErrLog("   tag: " + FmtGetField(format, "Tag"));
		 sec = FmtGetField(format, "Seconds");
		 ms = FmtGetField(format, "Milliseconds");
		 time = TimeIntToTimestamp(sec, ms, 1);
		 ErrLog("   time: " + TimestampToStr(time,14));
		 ErrLog("   value: " + FmtGetField(format, "Value"));
		 ErrLog("   quality: " + FmtGetField(format, "Quality"));

See Also

Tag Functions