Digital Waveform Acquisition with M-Series Card

[d-s-m]

I want to acquire digital waveform data with a M-series card (6220).
I found in the help file, that the digital acquisition part of the card has not an own sample clock and that it is necessary, to route e.g. an internal counter to the DI sample clock. I found no example, how to do this.
I've attached my example. I've configured a counter task with a period of 1 ms and an digital acquisition, that reads 1000 samples, so it should return the buffer every second, but the reading loop is running as fast as possible.

Thanks in advance
Dirk Schueller-Moeller

[Ingo_Schumacher]

Since you didn't include the configuration of the daqmx channels in your vi I can't tell if you are doing something wrong.
Because the DIO lines don't have an own timebase you need to supply a tact signal to time the operation. This could be an AI scanclock, or an AO update clock or any external TTL signal.
If you dont have a data acquisition or generation running synchroneously you always can use one of the counters to generate a continuous pulsetrain as a tact.

Here are some links to online examples:
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=E4C68BB4D82A126DE034080020E74861&p_node=%20DZ52321&p_source=External
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=DD535427AB1D5A53E034080020E74861&p_node=DZ52000&p_source=External

Attached you find an example using a counter as timebase