Using PFI 0 on cDAQ-9189 to trigger analog input channel

[svazquez22]

I am trying to use the PFI 0 channel in the cDAQ 9189 to send out a signal to set off a trigger threshold on my BNC Model 575 delay generator so that it can trigger 4 analog output signals to be sent out to and read by my NI-9775 module. I have a cable running from the PFI 0 channel to a channel on a separate NI 9775 module on the same cDAQ 9189. That channel has a splitter BNC connecter that also runs to the trigger on the delay generator. I was able to get this setup to work as I wanted with an analog trigger but now I would like to adapt it to be able to be done with a digital trigger. I have included my VI files, any help would be appreciated.

[ZYOng · Accepted solution]

You can refer to the following KB to output the signal from the chassis PFI.

How to Output a Digital Signal from a cDAQ PFI Chassis Terminal

You can keep the Analog Trigger on the NI-9775. You can also configure the task to use digital trigger from PFI without external wiring. See the attached example.

[svazquez22]

This seems to be working how I need it to work, but is there a way to run the vi and have it record my signal data as soon as it receives the signal from my delay generator? As it works right now, I need to run the vi, hit run on my delay generator and very quickly hit the start button on the front panel so that it records the signals. I would like the vi to wait for the signals and record them as soon as they are read by my NI 9775 module. It may not be possible as this is using a digital trigger but if it is possible, I would appreciate an explanation of how that can be achieved. Sorry if I am not being clear. I greatly appreciate your help thus far, it has gotten over a massive hump!

[ZYOng]

I am a bit confused on what you are trying to achieve. If you would like the vi to wait for the signals and record them as soon as they are read by NI 9775 module. The analog trigger would meet the requirement.

What is the purpose of trigger from the chassis PFI? The delay generator cannot synchronize its channels on its own?

[svazquez22]

So my generator has a trigger key that can read a signal and then once the voltage threshold is met, it tells the other four channels to fire off their signals. It can essentially keep all those signals on standby when I hit run on the generator while the trigger key waits for a signal. So essentially I would like the program to fire a trigger signal to my generator's trigger key and then immediately begin recording the signals that will be fired back to my NI 9775. I was wondering if there was a way to send out a signal like this from the PFI 0. I have included a picture of the generator I am using for reference. Hopefully that clears up any confusion. Again, your help is very much appreciated!

[mcduff]

I am kind of confused as to what you are doing. But could this be the solution to your problem...

On your digital trigger VI you set the timeout to 5s, why not set it to -1 so it waits indefinitely for a trigger from your delay generator. Why have a timeout?

If you need an escape, split the task wire and close it in another loop, that will error out the wait.

[ZYOng]

"So essentially I would like the program to fire a trigger signal to my generator's trigger key and then immediately begin recording the signals that will be fired back to my NI 9775."

You can remove the while loop from the program I attached earlier. Instead of Reference Trigger, you can try using Digital Start Trigger.

For the operation, first you hit run on the generator. Then take your time to run the VI. The VI should fire the start trigger to both generator and NI-9775 simultaneously.

[svazquez22]

Can the PFI 0 port send out a voltage signal?

[ZYOng]

Most NI DAQ uses TTL signal for digital. It is a voltage signal with 5V as high and 0V as low.

https://learn.sparkfun.com/tutorials/logic-levels/ttl-logic-levels

[svazquez22]

So if I wanted to send out this TTL from the PFI 0, how would I go about telling Labview to do that? Again, I appreciate all of your help up to now!