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DAQ and timing

Hi, 

I am using a NI USB 6356 DAQ to read data from 8 pressure transducers. We use a timing hub to control the rest of our experiment (cameras, solenoid valve, spark plug, etc) and I was hoping to add the data collecting from the pressure transducers to this as well. However, we use all the analog BNC connections for pressure cables and only have digital input connections available. Currently the VI I am using I have to make sure I press go/start/run each time I want to collect pressure data. Is there a way for me to press run and have the program not collect data until I also press run on the timing hub either in the VI or on the DAQ or both? I attached a copy of my current block diagram

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Your VI is taken pretty much from the example VI from NI.  So it has an entire section dedicated to triggering.  You just select the tab of the type of trigger you'd like to try, along with choosing a device and a channel, and it will defer taking the samples until whatever trigger method you have selected it satisfied.

 

For instance, I have a USB-6361 on my desk, and I can use your VI to trigger the measurement by setting the tab to "digital start", then selecting the source as "USB-6361/PFI0", and as soon as I send a 5V signal to pin 73 on my USB-6361 then the measurement gets taken.

 

Are you saying you want to want to replace this sort of trigger mechanism with software only?  Or do you have a digital switch that you want to physically press?

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After looking more into it I believe I am just having trouble with the APFI0 input. The timing hub only has BNC cables leaving it and the input for APFI0 is just wire. Do you know what specific wire goes into this?

 

Thank you.

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Are you sure you want to use the *analog* trigger line APFI0 rather than one of the more standard *digital* trigger lines PFIx?  See here for a little more info.

 

Your overall setup isn't real clear to me, so it's hard to give specific advice.  I'm basically kinda assuming that the "timing hub" puts out digital timing signals of various kinds, and that these signals get connected to the various equipment that needs to be sync'ed.  It would be normal for such timing signals to be digital pulses or clocks, hence my question about your use of the *analog* trigger line APFI0.

 

You'd probably want your AI task configured for a digital start trigger on a particularly PFI line and you would physically connect to the appropriate signal on the timing hub.  You'd probably be fine with a simple adapter from BNC to something that gets you to bare wire leads for a screw terminal.

 

 

-Kevin P

CAUTION! New LabVIEW adopters -- it's too late for me, but you *can* save yourself. The new subscription policy for LabVIEW puts NI's hand in your wallet for the rest of your working life. Are you sure you're *that* dedicated to LabVIEW? (Summary of my reasons in this post, part of a voluminous thread of mostly complaints starting here).
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