CompactDaq AI with Visual Basic .NET

[DieselPower]

Here is the project without Excel, but now I have an error whose message I have attached as an image.  It happens with I try to execute Reader(0).ReadMultiSample

Thanks

[Erik_J]

Hi Michael,

Hopefully, I have found the problem!  You are receiving the -200278 error because your timing mode is set to Finite, even though you are doing a Continuous acquisition.  This may be causing the slow acquisition rate as well.

Try this change, replace Finite with Continuous.

                Tasks(TaskCount).Timing.ConfigureSampleClock("", frm.numSampleRate.Value, SampleClockActiveEdge.Rising, _
                                                             SampleQuantityMode.FiniteSamples, frm.numSamples.Value)

Replace with

                Tasks(TaskCount).Timing.ConfigureSampleClock("", frm.numSampleRate.Value, SampleClockActiveEdge.Rising, _
                                                             SampleQuantityMode.ContinuousSamples, frm.numSamples.Value)

Please let me know if this solves the problem!
Thanks,
Erik

[DieselPower]

Now I am getting "Attempting to read a sample that is no longer available."

[Erik_J]

Hey Michael,

I think you are getting error -200279, Attempted to read samples that are no longer available. The requested sample was previously available, but has since been overwritten.

This error indicates that the DAQ card acquired samples, placed them on the buffer, and that the samples were overwritten before your .NET code could read from the buffer.  The buffer size is determined by the number of samples input, we may want to increase that number.

What numbers are you using for your rate and number of samples?

Thanks,
Erik

[DieselPower]

200 S/s and 1 or 2 samples per channel.  I'd like to keep my loop time under 500 ms if possible.  I am happy with one reading as long is it isn't subject to noise.  It seems to run very close to our SCXI system which is taking 100 samples and averaging them.  If I increase the number of samples I want, won't it take longer to respond?  Should I just decrease my rate?

[Erik_J]

Hey Michael,

If your goal is 1 or 2 samples per second, why is your rate set to 200 S/s?  I think that you are correct in that the rate needs to be decreased to 1 or 2 S/s.  I would suggest trying 1 sample per channel and acquire at 2 S/s (2 Hz).  This way, your loop will take 500 ms and you shouldn't get any buffer problems.

Regards,
Erik

[DieselPower]

Have you been able to get my software working on your computer?  The latest one with no excel reference.

[Erik_J]

Hi Michael,

I was able to get your code to run without error if I use 2 samples per channel and a rate of 2 S/s.  I am unsure where it writes to file though.

Erik

[DieselPower]

It's in bin\data where the application startup path is

[Erik_J]

Hi Michael,

I found the data file, it is attached.  I am still having trouble understanding your code.  It seems that no matter what I put in for the rate, it still samples at 1 S/s for me.

Erik