How to send trigger (digital pulse)

[labview.edu]

Hi,

I am new to labview, started this month only and am currently using express vi's. I would appreciate if someone can direct me how to send the digital trigger out.

Problem: I am using a beam with 2 strain gauge mounted, I am trying to send a digital trigger out when the strain value crosses certain threshold (For senior lab). Currently I can acquire the data and plot. But I am not sure on how to send the digital pulse out.

Hardware: Labview 8.5.1, SC-2345 connector block, SCC-SG01 Strain module, PCI-6251 DAQ Card and SCC-DO01 Digital Output Module.

Thanks,

Sine

[Jason_D]

Sine,

You could use the Trigger and Gate Express VI  using the Data available line to determine if you want write the digital line or not.

If you are using only express VIs then you will want to go to the pop up screen for your DAQ Assistant that is reading in the strain value.  There is a tab in the middle called "Triggering." 

I am not sure exactly what you want so am having trouble giving you specific steps.

Please let me know if you could not get you want from either of these places.

[labview.edu]

I have tried Trigger and Gate VI but I couldn't see the option of sending the trigger out, please correct me if I am wrong (pic attached).

Also in the triggering tab the same problem (pic attached). All I can find is the trigger to initiate the data acquisition process. But How can I also send the output trigger?

Problem :  I want to acquire the data as soon as the strain crosses certain threshold. But I also want to trigger the connected external hardware (accepts ttl/make/break) as soon as strain threshold is reached.

Confusion: How to send the trigger to the external hardware as soon as threshold is reached? 

I am using: Labview 8.5.1, SC-2345 connector block, SCC-SG01 Strain module, PCI-6251 DAQ Card and SCC-DO01 Digital Output Module.

Thanks,

Sine

[labview.edu]

bump 🙂 ... anyone?

[MattBradley]

Looks to me like you have it triggered to start taking data in LabVIEW when you exceed the trigger -- which isn't what you want (I think).  You want an output signal to some external device, right?

[labview.edu]

 My existing vi: As soon as strain value reaches certain value, strain acquisition (trigerred) starts and values are stored in a file. All done internally with-in the labview.

Modification I am trying to include: As soon as the strain acquisition is started, a trigger should be send to the external device. How can I do this?

Thanks,

Sine

[MattBradley]

I see... in that case, I think you won't be able to do it with Express VI's.  Are you OK with that?

[Dennis_Knutson]

This is a duplicate of this thread. Don't start multiple threads for the same question.

As explained in the other thread, you should look at the shipping examples for digital output. And of course, you can use an Express VI. Select a digital output task. The simplest is to have a True constant (oer the output of your comparision) on your block diagram wired to a Build Array function which is wired to the DAQ Assistant.