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How do I use PFI as a user input switch?

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Message 1 of 9
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Please put some words into the body of your message so that we can have some details on what you are trying to do.

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Hello.

I have a NI cDAQ-9188 that I am using to sample, display and log data. The user would like to add a "pickle" switch to the PFI port to signal an event to start or stop a process. I am having a difficult time trying to do this. Please advise.

Thanx.

Bill.
I was using IE9 but had to switch to google chrome to get text in the boxes.
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Message 4 of 9
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I assume that you're talking about starting/ stopping the actual data collection?  All you'd have to do is take your data collection VI (the picture below used the Acq&Cont Voltage example VI included with Labview), put a while loop and case structure around the VI.  You can wire your boolean switch to the case structure.  Just leave the false case blank and add a stop button of some sort to the while loop.  

 

Regards,
Austin S.

National Instruments
Academic Field Engineer
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Message 5 of 9
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Thanx, but I don't think that is it.

 

I've got a producer loop (essentially your VI example) pushing consumer data though a queue to update the UI or store to disc. What I need to be able to do is when the user pushes a hand held button that I want to connect to PFI 0, I am able to capture that event and then start my process state machine.

 

I've attached an outline of what I have been doing. I would much rather catch a screen event in an event handling loop but the user is attached to this external button.

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Message 6 of 9
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OK, thanks for clearing that up.  Below, I've linked a DevZone example/ tutorial that is using a digital start trigger from a PFI channel to start analog input & output using the DAQmx VIs.  I think what you're looking for to start your data collection is the DAQmx Start Trigger (Digital Edge) VI.  This will let you specify a PFI trigger source to begin the task.  Try this and see if this is more similar to what you were looking for.

 

Synchronizing Input and Output Channels using an External Start Trigger:

http://decibel.ni.com/content/docs/DOC-11645

Regards,
Austin S.

National Instruments
Academic Field Engineer
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Figured it out. I am so smart. S-M-R-T Smiley Tongue

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