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digital output with cdaq and ni 9474

I have a cdaq and ni9474 module. how would i go about generating a single digital high output pulse (from low to high, then low again). Ive tried various things in LV signal express and it generates a continous stream of pulses, or the output latches high all the time.

I also have access to labview if thats something that signal express cannot do.

The other error i get is an external clock is required?

The purpose of this would be to generate a trigger for a simple motion controller to move a motor as recording is activated for the DAQ.

Thanks!
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Hi

You should be able to handle this application from Signal Express and LabVIEW. In Signal Express you will add a Digital Output step. See Figure 1. You are getting that an "external clock" is required because you are probably already using your clock on another task. You may post your Signal Express project if you want.

 

figure 1

For logging the data the pulse I will kind of prefer using LabVIEW, especially example named: “Write Dig Chan.vi” where you can software timed your pulse and log the time when it was sent. What I ould suggest is to get the hardware part working first and then if you need help on how to log when the pulse is sent post your question in a LabVIEW forum.

I hope it helps



Message Edited by Jaime F on 02-21-2008 03:51 PM
Jaime Hoffiz
National Instruments
Product Expert

Digital Multimeters and LCR Meters
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Thanks for the reply back.

Thats exactly what I've done in Signal Express. However, my output remains high even after run/record is stopped. Is there a way just to send a singular pulse output or have the high return back to low after the recording is stopped?

Also I dont think the clock is being used by another resource since this is the only task I'm currently running (output module on the cdaq chassis).

Thanks!

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Hi,

I have been playing around with Signal Express and it seems to me you won’t be able to take the signal back to low when you stop the record automatically. You can still manually changed yourself. I guess you have a record that starts and stop automatically and when it does the line stays high. If this is the case you I don’t think you can automatically drive the line to low since this card is software timed, Signal Express controls the state of the line and you have to manually change it.  

This might be a job for LabVIEW. Did you have the chance to take a look at the example I pointed you?

Waiting for you reply

Jaime Hoffiz
National Instruments
Product Expert

Digital Multimeters and LCR Meters
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