Interpreta​tion of and solution to error message

Question

I am trying to use a PCI-5122 card in a Windows XP PC/LabView set up to receive input from a Sodium Iodide detector to create a Multichannel Analyzer for Gamma ray spectrometry.  It runs for a second or so then gives an error:
Error - 1074118632
niScope Fetch Cluster.vi:1
Driver Status: (Hex OxBFFA4018)
Data has been overwritten in memory and ....
Status Code -200004
What does this mean, and what can I do about it?  It appears that there is a lack of synchronization between the card and computer and somebody's (probably the computer) memory is getting filled and overwritten?
The Error Code vi says something like text unavailable and tells me nothing new.
Thanks
Gammarays

Answer 1

Hi Gammarays,
You're performing a continuous acquisition. You might have adapted it from the Fetch Forever example. You get the error because you aren't reading the samples in the circular buffer before they are overwritten. Many scope applications acquire records with reference to a trigger. Do you in fact need the continuous acquisition or does it make more sense for your application to continuously acquire?
With regards to "playing around with the Min Sample and the Number of Samples", you should expect to see fewer problems if you set your number of samples to fetch to a higher number. Since the timeout is set to 0, if fewer samples are present than specified in "Number of Samples" they will be immediately fetched. This should correct any problems related to the acquisition. If you are still experiencing problems, it may be due to any processing you're performing on the acquired data. I'd recommend offloading the processing to another loop. I've edited the VI you attached to show how this can be done with a producer/consumer loop. Since we were seeing some issues already, I limited the size of the queue and set a timeout on the enqueue element. I also added an indicator to display whether you ever timeout (this would indicate that your processing loop is lagging behind and it can't keep up with the acquisition speed).
Mike Lyons
National Instruments
http://www.ni.com/devzone
Attachments:
MCA test.vi ‏110 KB