08-19-2010 05:38 PM
I am trying to recreate a simple feedback control system using a cDAQ 9172 chassis as shown in this demo video:
I have the NI 9233, NI 9215 and the NI 9263 modules available for IEPE analog input, analog voltage input and analog voltage output respectively. In my application, I am using an IEPE accelerometer and hence I am using the 9233 and 9263 modules for input and output. While the "1 Sample (on demand)" timing setting works for voltage input from the 9215, it doesn't seem to work for the IEPE input module 9233 (I get an error code: 200077). I do not see any such limitations in the 9233's documentation. Does someone have an idea why this would happen given that the chassis itself is capable of SW timed single point mode? Is there a workaround?
08-19-2010 06:06 PM
Since the 9133 is a DSA device has a minimum number of samples, which is two. I think this document will help address the question you are having. You may want to consider just setting up a hardware timed acquistion with a slower sampling rate or increase your rate and discard un-needed samples. Hope this helps out!
08-19-2010 09:47 PM
Thanks for the quick reply. Just making it clear that I made a typo on the heading... It should be 9233 and not 9133. The document that you linked says that "A single sample can be acquired if the acquisition is software timed." I also tried hardware timed acquisition and it returns the same error code. I suppose the cDAQ 9172 & NI 9233 combo works only for finite and continuous sampling settings.
Increasing the sampling rate makes sense since it reduces the digital delay in DSA devices (as explained here: http://digital.ni.com/public.nsf/allkb/F989B25FF6CA55C386256CD20056E27D).
I will try it out and let you know.
08-20-2010 08:56 AM
I too made the same typo, I was probably looking at the heading! I was, however, speaking about the 9233.
Here is probably the error you are receiving:
-200077 is the "Requested value is not a supported value for this property." and the property in question is the type of timing being used. The "On Demand" or software timing is not supported for this hardware. If you notice the error on the KB I linked to last post its the number of samples that is not supported in that case for that device. In this case it is the software timing. Post back if you have questions!