Restarting Task After Performing Shunt Calibratio​n

Question

Hi,
I wonder if anyone can help with a problem that I am having with LabVIEW 8.5. I am using LabVIEW to measure strain gauges via SCXI 1520 signal conditioning units.
To perform a shunt calibration of the gauges I use the National Instruments example code.  The problem seems to occur after the  'CalculateGainAdjust.vi' has been called. The DAQ task is passed to the calibration code, 'CalculateGainAdjust.vi' does the following:
*passes the clock configuration to the end of the VI so the original state can be restored.
*enables shunt calibration
*creates a new clock
*starts task
*reads 1000 samples
*stops task
*disables shunt calibration
*restores task state
This code executes without causing an error. If the main DAQ task is stopped and then a calibration performed the task will not restart with its original configuration and times out with the following error:
Error -200284
DAQmx Read (Analog 1D Wfm NChan NSamp).vi:11<append>
<B>Property: </B>RelativeTo
<B>Corresponding Value: </B>Current Read Position
<B>Property: </B>Offset
<B>Corresponding Value: </B>
If a calibration is performed before the DAQ task is started then the DAQ task starts ok after calibration.  It is only if the task is run then stopped to perform a calibration that the problem occurs.
Is it necessary to take into account the 1000 samples read during the calibration process? I wonder if the main DAQmx Read VI is waiting for the 1000 samples that have been already read ? Strangely enough I don't think this was an issue when the code was run on LabVIEW 8.2
Any suggestions would be appriciated
Kind Regards
Ian

Answer 1

Hello Ian,
Thank you for the link pointing to the downloaded examples that you have been using.  More importantly, I am also glad to see that you are able to use the examples and that you found an order of operation that does not cause any error codes.  You are, however, interested in continuing searching to find what causes the error in the latter case of operation, which is what I will be helping with. 
Just to be sure, I have a Knowledgebase Article linked below to help avoid the error, -200284. 
http://digital.ni.com/public.nsf/allkb/FEF778AD990​D5BD886256DD700770103?OpenDocument
As we said, the error can occur in the latter case because something is not being setup correctly with the DAQmx task, or because the Calibration procedure is making use of the the hardware resource, and not releasing it for the DAQmx task.  I will have to do more research, and reply back confirming the cause.
The examples you are using seem to be the most current, although I will take the time to compare them with those that ship with LabVIEW 8.5, which you currently have.  The examples have been available since the release of the modules.  As the modules have not changed, it appears that examples are at their optimum level.
Regards,
George T.
Applications Engineering Specialist
National Instruments UK and Ireland