one point digital trigger

[cpeterh]

I am trying to convert "one point digital trigger" (a DAQ example for E series board) for one that runs on the 621x series, which have similar I/O.  No joy.  The closest I come is one that hangs both labview and my computer, which I enclose. Any ideas?

[Chris_W.]

Hello,

I opened your VI, and it looks like you are just trying to output a voltage waveform based on a digital trigger. There is an example in the NI Example Finder that does this, that I think you should base your development on. If you open up the NI Example Finder (Help>>Find Examples) and browse to the folder path Hardware Input and Output>>DAQmx>>Analog Generation>>Voltage>>Cont Gen Voltage Wfm-Int Clk-Dig Start.vi.

This should give you a good idea of the proper way to set up a DAQmx task to perform this type of voltage output. It wasn't clear what exactly you were trying to do in your code, because I didn't have the VI named  Modified AO wait ph.vi, but I think should help you get started in the right direction.

Chris W

[cpeterh]

Of course, I used this as my basis - but I want to output not a waveform, but a single voltage which stays on until the vi is stopped.

Whenever I try to do this, replacing the example sine wave with a single value, it tells me my buffer is too small. Hence I added the set buffer vi - but the problem of the vi hanging arose.

If you replace the ao wait with a simple write, the same thing happens.

[Dennis_Knutson]

Your code is confusing and without the subVI, can't really understand what you've done. With a single point to write, I have no idea why you are using the sample clock or the buffer size functions. It seems all you need is a DAQmx Write set for 1Chan 1Samp.

[cpeterh]

I tried that - does not like a trigger without a clock.  So I found this example below - looks great.  Except when I run it, I get an error code 200077 "Measurements: Requested value is not a supported value for this property."

[Chris_W. · Accepted solution]

Hello,

Hardware timed single point timing is different than what you're going for and as the error message is not supported on your card. You are also correct that that you cannot use triggering with a static generation. Since this is the case, why don't you just create a waveform that is multiple samples of the same voltage and perform a finite generation with this waveform. But, you will want to make sure not to clear this task until everything is done, so it does not reset the card and it's configuration and it hold the last value that was output.

Chris W