How Do I enable multiple trigger voltages on the PCI-6221 using NI-DAQmx?

[capncane]

I am using the PCI-6221 to do some simple data acquisition.  The idea is to allow three different analog voltages to trigger the data acquisition state.  I currently have the code set up for one voltage trigger but I am not sure what needs to be done to add the two additional trigger voltages. Any ideas?

Thanks.

[Steven_K.]

Hi capncane,

The PCI-6221 does not have analog hardware triggering so what you will need to do is to acquire the triggers and your data signal continuously. Then setup a data manipulation, where you drop data points if the trigger conditions are not met. If the conditions are met, keep the data. I hope this helps. 

[capncane]

Is it possible to do something as simple as this:

    DAQmxErrChk
        (DAQmxCreateAIVoltageChan(taskHandle,"Dev1/ai0","",DAQmx_Val_Cfg_Default,0.0,5.0,DAQmx_Val_Volts,NULL));
    DAQmxErrChk
        (DAQmxCfgSampClkTiming(taskHandle,"OnboardClock",3000.0,DAQmx_Val_Rising,DAQmx_Val_FiniteSamps,3000));
    DAQmxErrChk
        (DAQmxCfgAnlgEdgeStartTrig(taskHandle,"Dev1/ai0",DAQmx_Val_Rising,0.7));

or will I need to put the trigger on PFI0?

[Steven_K. · Accepted solution]

Hi capncane,

The 6221 is not able to do analog triggering so DAQmxCfgAnlgEdgeStartTrig will not work for your card. Is your trigger a digital signal? If so what kind of level logic is it? If it is TTL you can use the PFI lines. If not you will need to trigger like I mentioned in my previous post.