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For simplicity, I have my generation session's Data Active Event exported to PFI0 and I have my acquisition session's Start Trigger configured to monitor PFI0.  However, due to RTD I have a timing shift in data.


The help document specifies an attribute "NIHSDIO_ATTR_DATA_ACTIVE_INTERNAL_ROUTE_DELAY" can be used to generate a delayed start trigger.  In addition it states:

You can configured the delayed Data Active event as the source for any acquisition trigger by manually entering DelayedDataActiveEvent as the triggerSource parameter. 

I have no trouble in setting the attribute, but I have not been able to find how to USE the "delayed" data active event.  It doesn't seem to be a signal that I can export to PFI0, nor does it seem to be a location that I can configure the acquisition start trigger to look at.


I am using niHSDIO dll revision 1.5.3


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Accepted by topic author broke

Hi broke,


There are two standard methods of eliminating round trip delay from your measurements:


  • You can use the DelayedDataActiveEvent signal to start your acquisition.  When using this, you can set the number of sample clock cycles to delay your acquisition to account for RTD using the Internal Route Delay attribute.  I would look at the RoundTripDelayElimination example to see what this looks like in C coding.  You can find the example by default here: C:\Program Files\IVI Foundation\IVI\Drivers\niHSDIO\Examples\c\Measurements\RoundTripDelayElimination

  • Alternately, you can physically wire the DataActiveEvent through your DUT and back to the HSDIO board.  This would give the DataActiveEvent the same round trip delay as the data itself.

It sounds like you are on the right track with the DelayedDataActiveEvent, let me know if you have any questions about the examples or have any problems eliminating the RTD.  Thanks for posting and have a great day!





Message Edited by John P on 04-16-2009 02:17 PM
John Passiak
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Thank you for the solution John.


My help files do not contain reference to "DelayedDataActiveEvent" as a valid entry for "NIHSDIO_ATTR_DIGITAL_EDGE_START_TRIGGER_SOURCE".  (It just lists PFI, PXI_TRIG, RTSI, and PXI_STAR entries...)  "DelayedDataActiveEvent" is also not in the include file for the driver...  I should remember to look through examples before giving up!




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