Signal Express trigger and process multiple AI channels.

[philwak]

A power analyser application requires a trigger on voltage to then process voltage and current waveforms. I am able to software trigger but then triggered data does not line up with other captured channels. Are these parallel tasks and hence triggered data gets out of synch with latest data? DAQmx is running as continuous and I run Signal Express as "Run once". Step sequence is DAQmx Acquire(continuous), Software trigger , then Arith to turn voltages from p-p to p-n, need to display raw data in sync with triggered data.

Note that my trigger options in DAQmx config have signal triggers greyed out, only none or software can be selected. Ideal would be to trigger on raw data and then process a block of N samples.

[TheWoost]

Hi,

Using the software trigger causes the most recent samples in the onboard buffer of the DAQ device to transfer into the PC memory and ultimately be displayed in software.  The number of samples that are displayed when you perform "Run Once" is dictated by the value you set for "Samples to Read".  Because the signal triggers are greyed out in SignalExpress, it sounds like the device you are using does not support them.  What DAQ device are you using?

Regards,
Andrew W
National Instruments

[philwak]

We are using Compact DAQ USB, AI is 9215. Is there any way of capturing more than one channel with the software trigger?

[Abhinav T]

Hi,

You should be able to group all your channels by pressing the Add Channel button (+) when setting up your acquisition.