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tclk trigger from which channel

I have a PCI with two NI-5114 in it and I am using t-clk to syncronize a trigger from one digitizer with the other.  I set up the trigger such that all the 5114 are immediate trigger except one which has an edge trigger on one of the channels.  When the trigger is channel 0 on the first digitizer the traces that come out of both N5114 are synced; however, if I set the trigger to be on channel 1 of the second digitizer then the traces that come out are not synced.  I can't test the other channels as I have no inputs in to them.


So my question, do I need to do something special when setting up the t-clk (calling niTclk configure, sync and initiate) or do I need to do something special when setting up the trigger on each digitizer?  I need the ability to change which channel I trigger off of.


Thanks, I can provide more info as needed.

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Hi GreenRiver,


For future reference, questions regarding hardware and more specificically our High-Speed Digitizers should be posted to the Digitizer boards so that you can get the most visibility from engineers and customers who are more familiar with these products.


In regards to your triggering, the only thing you should need to specify is the trigger source on the on the niScope Configure Trigger Edge function. If you are starting from the niScope EX Multi-Device Generic Sync example in LabVIEW, make sure that the case that configures the trigger is "1". This will make it so the second device listed in the Resource Names array will have it's channel 1 configured as the trigger source. If you have everything set up this way, posting your code here can prove useful for troubleshooting.


Paul C

Paul C
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I have a slightly modified niScope EX Multi-Device Configured Acquisition.  In the orginal the VI sets a trigger on the first device listed, I changed the outside case structure so I can change which device it triggers off of while running inside the main loop.  I found that it triggers properly at first after starting the VI, but when I change which device it triggers from then that new device will trigger as configured but the other device (the orginal) will not (the two triggers are not synced).  If I go back to the original device that I had selected then the triggers will be synced agian.  It doesn't matter which device I have selected first.


I feel like it ust do with how I am changing/setting the trigger of the devices or the tclk setup.  I attached a picture that shows my changes to the vi example.

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Thanks for posting those screenshots. I have a couple of suggestions. In the true case for configuring the Trigger Source Edge, I would create a control and just select which channel you would like the device to trigger on in that way. This input is a type definition because it wants to make sure whatever you input into this node is within a certain format. Also, for the false case, instead of using an immediate reference trigger, just wire through the case structure. once you configure the analog edge reference trigger for your second device, the TClk functions will take care of the synchronization of your devices. The way you have it set now, they are not sharing a common trigger, which is why you are seeing asynchronous behavior.

Paul C
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Thanks for the reply.  I agree with your first statment, this was just for a quick demo to see if I can get the digitizers to trigger the way I want dynamically.


The second suggestion about wiring stright through doesn't do what I want either.  I attached two pictures that describe the behavior of my way and your way.  They behave differently when the channel/device to trigger from is changed but neither is the behavior I want.


In the way I was doing it (picutres posted a couple comments up) the two traces on the two devices are synced as expected (two sine waves with a 45 degree offset) but when the VI is running and I switch the device/channel for the trigger then one of the waveforms is triggered on the edge, but the other is just randomly triggered and the two are not synced.


With the wires feedthrough in the false case as you suggested then the two devices are synced when I start the VI, but when I change the device triggered then both waveforms are triggered on the edge but agian are not synced to each other.


The two pictures I attached should give a visual of both cases, they are a screen shot of the waveforms before and after the device is changed.



Just to make sure you know what I am trying to do, I want to change which device/channel I trigger from (always an edge trigger) while the VI is running.

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