Re: compare timestamps of two independent reference triggers using counters

[BrissyDrew]

Hi Tnek,

Thank you very much for the prompt reply to my post. The solution you presented is exactly what I want. However I am having a little bit of trouble implementing it.

I started by loading up one the Labview Examples titled "Meas Two Edge Separation.vi"  (screen shot attached) however it immediately returned at -200431 error which I haven't been able to interpret. Have you come across this error before with the PXI-6133 boards or have I wired up the wrong input?

Regarding the routing of internal signals, just wondering how I select "auxiliary line input" as described in http://zone.ni.com/devzone/cda/tut/p/id/4529  when exporting signals. Attached is a screenshot of the configuration I have now for exporting signals but I am unsure if it is correct.Any further help would be greatly appreciated.Cheers,BrissyDrew
Message Edited by BrissyDrew on 07-27-2008 09:31 PM

LabviewError12.JPG:
http://forums.ni.com/attachments/ni/40/6595/1/LabviewError12.JPG

export_signals.jpg:
http://forums.ni.com/attachments/ni/40/6595/3/export_signals.jpg

[Brooks_C]

Hello BrissyDrew,

 

Unfortunately it looks like the PCI-6133 does not support two edge separation measurements--that is the source of the -200431 error.  In order to determine the time separation between your two reference triggers I think you're going to have to use digital lines.  If you route the reference trigger signals to two digital lines and use the 1 MHz clock as the sample clock you should be able to use software calculations to calculate the separation down to +/- 1 us.  It won't be a direct measurement, but the result will be pretty accurate.

 

If you have another data acquisition board (i.e. E or M Series multifunction DAQ) then you may be able to take Tnek's suggestion to do the two edge separation measurement by routing signals to that card.  Otherwise you'll have to monitor these two signals and measure the separation in software.

 

Also, with regards to the aux line, this is a related issue, and likely the reason the two edge separation is not supported on the PCI-6133--the counter aux line is not available on the pinout.  On devices that support this measurement you would see CTR X AUX on the pinout.

 

I hope this helps, and have a great day!