Analog voltage comparison to raise a digital output

[ManRaob]

I am using NI DAQ PC-6225 and using it to read Analog voltages and digital inputs using a C program

I want to add additional functionality to compare a Analog voltage in a C program against a threshold value and trigger a digital output whenever the threshold is exceeded.

The documentation gets pretty confusing and when I use the DAQmxCfgAnlgEdgeStartTrig funciton it did not work.

I am hoping to find a pointer to an example that will let me set this up.

your help is appreciated.

ManRaob

[Dennis_Knutson]

As you can see from the specs, your board does not support analog triggering.

[ManRaob]

Thanks. Any other options to achieve the result with this board?

Best

ManRo

[Henrik_Volkers]

How about using a simple discrete comparator and a software controlled analog reference plus a digital output for power/enable? 

The LM393  is an old standard... or use the LT1394

[ManRaob]

Thanks Henrik. That is an option.

I have 22 systems in the lab and was hoping for a software solution to get this done.

ManRoab

[Dennis_Knutson]

The software solution would be to read x number of samples, compare each to your threshold, and doing the DAQmx Write of the digital output under software control. There, of course, would be some lag in this since you would have to wait until x number of samples are acquired.