How do I wait on a PXI_TRIGx transition?

[wired]

I am outputting a 1 pulse-per-second pulse from a ZTEC1000PXI GPS card to a PXI_TRIG line.  Is there a way I can create a thread to wait on this line to go high so that I can read the GPS position information at the 1-second rate?  I also have PXI-6120 and PXI-4472 boards in the system.  I don't want to do any polling of the PXI_TRIG line, because I am also going to need to perform a number of HS data acq and streaming tasks.

Kevin 

[Krista H]

Hello Kevin,

I have a few questions about your post. First what environment are you programming in? What do you want to use to read the GPS position with? One of your DAQ cards, or the ZTEC? If this is going to be read by the ZTEC card then we will not be the best help for you on this. You might try contacting ZTEC.

If you are trying to use the PPS or the GPS with our DAQ cards please reply with more specific information about what you are trying to accomplish. I definitely want to help you out here but I really need more information on this.

[wired]

Krista,

I am programming in LabVIEW, and am using the ZTEC ZT1000PXI GPS card for a number of functions, including generating pulses and clocks on various PXI_TRIG lines.  Many of these signals will be routed to the DAQ cards as sample clocks, start triggers, or timebases, but in one particular case, I do not want to perform a DAQ function at all.  I just want to use the PXI_TRIG line as some type of trigger to LabVIEW that an event has occurred (just like an interrupt), so that I can perform some queries of the GPS card (timestamp, location, etc) as soon as possible after I receive this trigger.

What I'm looking for is something like a Wait on Occurence, where the occurence is the rising edge of the pulse received on the PXI_TRIG line.  I would then use a subroutine-priority VI to acquire the information from the ZTEC card as quickly as possible.  What I am trying to do is basically have a LabVIEW-based interrupt service routine, with the interrupt being the rising edge of a PXI_TRIG line.  Is there some way to do this?

Kevin

[Krista H]

HI Kevin,

Thank you for the further explanation, that really helped. I think that you should look at DAQmx Events. There is a great example of this in LabVIEW. To access it please, in LabVIEW, go to Help>> Find Examples. Then the example is found under; Hardware Input and Output>> DAQmx>> Events. The best example for you would be the Gen Event for Ext Signal and it will work best with you 6120 S series DAQ card. Please look at this and let me know if you have any questions.

[wired]

Krista - I found that example this morning.  It is an option for me, but I was really wondering if there was a way to do it without involving DAQMX - a lower level way to get to the PXI trigger line and generate some type of event when it goes high.  I was trying to avoid having to identify a DAQ device and use its resources for the operation.  Is there no other way other than through DAqMX to get access to the PXI_TRIGn lines?

[Krista H]

Kevin,

Basically if you want to trigger off the PXI trigger line then you will need to use one of your cards. The Daq card is the best one to use. There is a lower level way to do this, but it will still be using your Daq device and resources. The trigger line is simply a line that you can trigger off of. I hope that this makes since to you. Please let me know if you have any questions.