Trying to acquire data with a PXI-5105 and PXI-6221 simultaneously

[ShawnS]

I’m trying to continuously record pressure data from a PXI-5105 digitizer at 200kHz and thermocouple data from a PXI-6221 DAQ at 1kHz. I’m using a PXI-1033 Chassis, ExpressCard, and a laptop along with the Digitizer and the DAQ.

I’ve tried a few times to record the data at the same time but I’m only able to get the DAQ or the Scope to run at a time. Currently, I’m using the example, “niScope EX Save to File – HWS Low Level – Single Channel Stream.vi” with the DAQ running in a separate parallel loop in the same VI. The DAQ runs fine but I get the error, “Maximum time exceeded before operation is completed.”

Is it possible to continuously acquire data from both sources at the same time? If it is, what should I watch for to be able to do this?

Thanks

[Steve_B]

Hi ShawnS,

Are you working with a DAQ example and if so, which one is it? You could be waiting for a trigger and if it does not happen you would receive a time out error. You should be able to run both of the acquisitions at the same time in the manner you described. A screen shot of your code if the issue is not triggering may provide some additional insight.

[ShawnS]

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I changed the rate on the digitizer to 250kHz and the code worked perfectly. It seemed like anything below that rate and NIscope would give me that above error. I’m curious to why this might be the case or if there was a way to get around that limit.

I’m using code very similar to the DAQ example, “Cont Acq Thermocouple Samples-SW Timed.vi” in parallel to the other example.

Thanks,

Shawn

[Steve_B]

Hi Shawn,

I was under the assumption that you were receiving the error with the DAQ loop. The error meant that your scope acquisition was timing out. What were you using as the record length for your acquisition? The example was set to record 2000000 samples for each record. You were acquiring data at 200kHz which would take 10 seconds to acquire that amount of data. The timeout value for the Fetch VI was set to 5 seconds by default in the example. The change to 250kHz would allow the card to acquire that amount of data in 8 seconds. Did you change the timeout value?