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Output pulses on two channels


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7 replies to this topic

#1 DanHickstein

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Posted 23 July 2012 - 10:42 PM

Hi there, We are trying to use our LabJack to trigger both a mechanical shutter and a CCD camera simultaneously. Both devices are triggered with simple 5-volt TTL signals. However, during each experiment, we need to send two pulses to the camera but only one pulse to the shutter. Also, since the shutter is slower to respond than the camera, we need to be able to set the relative delays of the pulses. Basically, we want to use Matlab to tell the LabJack to "Go". After we tell it to go, it should send one pulse to the shutter and two pulses to the camera simultaneously with ~1 ms timing. Is such a thing possible with the U6? I have the basic analog output working from the LabJack using Matlab, but I don't have a good idea of how to program the simple pulse sequence into the device. Any hints would be appreciated. Cheers, Dan

#2 LabJack Support

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Posted 24 July 2012 - 09:30 AM

Sounds like an Add-Go-Get block with the PUT_WAIT iotype might do what you want. Search labjack.com using the term "LJ_ioPUT_WAIT". Following are a couple good links to get you started:

http://labjack.com/s...rs-guide/4.3.14

https://forums.labja...?showtopic=2969

#3 DanHickstein

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Posted 27 July 2012 - 03:00 PM

Thanks a bunch for your response! We were able to get the LabJack working to deliver the signals to the shutter and camera and they work great! This was an easy and inexpensive solution to this problem. The jitter is about ~500 microseconds, which is acceptable. I have one more question. Ideally, we would like to trigger the LabJack from an external rising-edge signal from a photodiode. Can the LabJack be configured to "Go" from an external signal? Many thanks, Dan Hickstein

#4 LabJack Support

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Posted 27 July 2012 - 03:32 PM

There is nothing in hardware like that on the U6. Software would have to poll the U6 to watch for the event of interest, and then send the command to make the pulses.

#5 DanHickstein

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Posted 06 August 2012 - 03:24 PM

Thanks for the info! Is this a feature on other versions of the LabJack? Cheers, Dan

#6 LabJack Support

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Posted 07 August 2012 - 06:36 PM

New T-Series LabJacks will have scripting which may make 100us response times possible.

#7 DanHickstein

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Posted 08 August 2012 - 08:58 AM

New T-Series LabJacks will have scripting which may make 100us response times possible.


When you say "scripting", you mean that it will be able to be triggered from an external TTL signal? Any external signal?

When will these fancy new LabJacks become available? Can we help you test one? :) We're just up the road at CU.

All the best, Dan

#8 LabJack Support

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Posted 08 August 2012 - 10:05 AM

By scripting I mean that you can write a Lua script to run right on the device. The script can constantly check the trigger line without being slowed down by USB communication time.


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