Finite Pattern I/O with Triggering

You can use triggering to control the start and/or stop of the digital I/O process. The trigger event can be one of the following:

•Rising edge of a digital pulse

•Falling edge of a digital pulse

•Pattern match trigger, where the trigger event occurs when data on the lines being monitored matches a specified pattern

•Pattern not match trigger, where the trigger event occurs when data on the lines being monitored differs from a specified pattern

The Buffered Pattern Input-Trig VI, Buffered Pattern Output-Trig VI, and Start & Stop Trig VI show how to use the triggering features on the 653X devices. Refer to the VIs in the examples\daq\digio.llb for examples of how to use the triggering features.

Continuous Pattern I/O

In this mode, digital data is continuously acquired or generated until the user stops the process. The data is stored in a circular buffer in memory in order to reuse finite computer memory resources.

Circular buffering for input works in the following manner. While the buffer is being filled by data acquired from the board, LabVIEW reads data out of the buffer for processing, for example, to save to disk or update screen graphics. When the buffer is filled, the operation resumes at the beginning of the buffer. In this manner, continuous data collection and processing can be sustained indefinitely, assuming your application can retrieve and process data faster than the buffer is being filled. A similar buffering technique is used when generating digital output data continuously.

The Cont Pattern Input VI, Cont Change Detection Input VI, and Cont Pattern Output VI show how to continuously acquire or generate digital data. Refer to the VIs in the examples\daq\digio.llb for examples of how to continuously acquire or generate digital data.