Continuous analog output intermittently dropping

[sambady929]

I've got a setup with a computer, a USB-6221 and a USB-6251. I have one continuously outputting an analog waveform and the other one sampling data. Every couple minutes, the waveform will stop being output for a small amount of time. I'm using a Visual Basic program to do this. Here's the snippet of code that sets it up. This issue only happens on computers running Windows 10, while with Windows 7 it's fine. Does anybody know if there's a setting in Windows 10 that messes with communication to the DAQ?

AO
DAQmxErrChk DAQmxCreateTask("", AOFastHandle)
DAQmxErrChk DAQmxCreateAOVoltageChan(AOFastHandle, "Dev" + Trim(Str(Sys.FastBoardNum)) + "/ao0:1", "", -10#, 10#, DAQmx_Val_VoltageUnits2_Volts, "")
DAQmxErrChk DAQmxExportSignal(AIFastHandle, DAQmx_Val_Signal_SampleClock, "/Dev" + Trim(Str(Sys.FastBoardNum)) + "/PFI5")
DAQmxErrChk DAQmxCfgSampClkTiming(AOFastHandle, "/Dev" + Trim(Str(Sys.FastBoardNum)) + "/PFI5", ClockFreqHz, DAQmx_Val_Rising, DAQmx_Val_AcquisitionType_ContSamps, 1000)
Call DAQmxWriteAnalogF64(AOFastHandle, npts, False, 10#, DAQmx_Val_GroupByScanNumber, AOBuffDP(1), nWritten, ByVal 0&)

DAQmxErrChk DAQmxStartTask(AOFastHandle)

[Alex.W]

Hello sambady929,

First, I would make sure that the drivers that you are using are supported for Windows 10.

Some additional questions I have for you are:

Does the waveform start again?

What does the waveform do when it stops (is it zero, does it hold the value, does time not continue, etc.)?

Can you output the data to a table and see if the data is also stopping or is it only the waveform?

Try to scope the output and make sure that it is not stopping.

[sambady929]

I'm using the latest drivers, which say they are compatible with Windows 10. I'm later going to try formatting the computer with Windows 7, because the set up works just fine with Windows 7. And that's the bizarre part, when I run the cards at 1250kHz(the rated max) I don't have any issues but my needs are at ~1500kHz, which is where I see issues. For some reason, though, I can run the cards at 1500kHz on Windows 7 with no issue at all. The computer I'm running Windows 10 does have updated hardware though, so I'm not sure if the issue is software or hardware related, but I'll be able to see once I put Windows 7 on it.

The waveform does start again, it's an instantaneous drop and instantaneously comes back. It wouldn't be a huge issue but it happens often enough that it affects the results.

The waveform drops to 0V. It should be ramping from 3V to 6V then dropping to -5V (to drop below the laser turn on) for a tiny amount before jumping back up to 3V and ramping. Instead for a couple waves it outputs 0V.

I can't tell if it's a USB issue or if it's a problem with the card. I've been monitoring the USB and haven't seen any interruptions with it but I might not be using the best tools to look at it.

[Alex.W]

Hello sambady929,

As you have stated when you are using the card within our specifications (1250kHz), the devices work as expected. However when you are using the NI devices outside of the quoted specification (~1500kHz), you see the unexpected behavior. We only can support the behavior of our products when they are being used within our specifications because we know what the device’s expected behavior should be.

Sorry but I cannot support the behavior of our products outside of its specification.

[sambady929]

After running the card at 1250kHz for almost 5 days, I noticed it actually does still drop out, though it's only dropped out twice.

[Alex.W]

Does the signal drop out on both Windows 7 and Windows 10 after running for five days at the maximum rate?

[sambady929]

It does not drop out on Windows 7 at the maximum rate or even at 1500kHz. The computer running Windows 10 is also using updated hardware. I tried installing Windows 10 on the older Windows 7 computer, but the older computer uses a CompactFlash card as its hard drive, which Windows 10 does not seem to support. I may try installing Windows 10 on an external HDD and running it off of that.

[Alex.W]

Try Windows 10 on the external HDD and see if the drop outs still occur within the expected operating range. Your physical hardware may be what is making the difference.

[sambady929]

Has this problem been observed on any other Windows 10 computers?

[NIYiran]

Hi sambady,

I have not heard of this issue, nor could I find anything in our internal searches. Have you been able to reproduce this issue on another computer with Windows 10? Also, do you notice any patterns of when the output drops?