High-Speed Digitizers

[Penny]

Hello again,

I am trying out some high sampling rates (25 Ms/s) on our USB 5132 using the NI shipping example FetchForever in VS 2008 C#.NET .  Something is not optimized because even if I only grab 1 point per Fetch, the example crashes after a few hundred Fetches with:  

Error BFFA4018.
Possible Reasons: 
The requested data has been overwritten in memory so it is no longer available for fetching.
Status Code: -200004 . 

Can I tweak the Fetch timeout, or do a Thread.Sleep, or something like that?  Or, am I going to have to close the session to the 5132 between Fetches as was suggested in this post at http://forums.ni.com/t5/High-Speed-Digitizers/StreamToDisk-with-repeated-fetching/td-p/1727894 ?

Thanks,

Penny

[Penny]

Hi,

It seems to me that a 'trigger hold' would be helpful in this situation, so that I could finish acquiring before the next (immediate) trigger.  However I see that the 5132 does not support trigger holds, as in http://zone.ni.com/reference/en-XX/help/370592N-01/digitizers/features_supported_smc_pxie/ .  Is there some other way that I can have immediate triggers from the 5132 without running into this problem?

Thanks,

Penny

[Penny]

I just added a 15 second Thread.Sleep in my code after the call to                      sampleScopeSingleRecordReader.MemoryOptimizedFetchFromMultipleChannelsAsync() and got the same error.  Any other suggestions would be greatly appreciated.

Thanks,

Penny

[Penny · Accepted solution]

Hi,

OK, it is all fixed now.  I went back to what I understand to be 'single record' acquisition, and then added a polling loop after the Fetch:

scopeSingleRecordReader.FetchFromMultipleChannelsAsync(channelNameTextBox.Text, 0, sampleScopeSession.Timing.ActualRecordLength, PrecisionTimeSpan.FromSeconds(50), null);

                            do
                            {
                                MessageBox.Show("fetched.  waiting for scope session to close.");
                                Thread.Sleep(1000);
                                
                            } while (sampleScopeSession.IsOpen);

 Sorry for clogging up the boards.  These digitizers are tricky.

Regards,

Penny