cDAQ 9174 does not work in the Bay area

[vsun]

Hi

I have a bit of a strange problem. We have been using a cDAQ 9174 to gather voltage data. It works fine when we use it in our lab in San Clemente, CA. However, when we bring this same cDAQ up north to our lab in the Bay area, it no longer connects with the laptop. We plug it in the same way, but the computer does not detect the cDAQ while at Northern California lab. While at San Francisco International airport, I even tried connecting the cDAQ to my computer while waiting for my flight, and it did not connect with the computer then.

But when we arrived back in San Clemente, CA and tried the cDAQ the next day, it connected and communicated fine with the computer.

This is with the same laptop, cDAQ, and power and usb cables. The only thing that has changed is the location. We have brought this cDAQ up north 3 times and every time it never works up north, but the next day back down south in San Clemente, the cDAQ works.

Can someone explain what is going on? Its hard to troubleshoot because right now the cDAQ is working fine while we are in San Clemente.

Thanks

[Knoxberry]

Hey vsun,

Is the laptop plugged in in both locations? Do you have anti-virus software installed that could have different configuration settings based on your network? What do you mean the computer doesn't recognize the device? Does it not appear in MAX? Does it not appear in the Windows Device Manager? Something has to be different between the two locations causing that behavior.

Regards,

[Neil_S.]

That is very strange.  I'll try to keep my ridiculous ideas to myself (Have you tried in LA, perhaps try it along the route to see when it stops working, etc.).  I agree with the AE, you should try to figure out what other factors are involved.

When you say it doesn't communicate with the computer what do you mean?  Does it not show up in MAX?  Does it show up in device manager?  Which LEDs on the 9174 light up?

Are there differences in what the 9174 is wired to at the two sites?  Is there any difference in the power or grounding of either the chassis or the laptop between locations?  I don't think virus scanning or network settings will be responsible since it is the same laptop and the 9174 is a USB device, but analog power issues could be a problem if you have strange grounding issues in the Bay area lab.   If I had to venture a wild guess I would say it had to do with a ground differential between the laptop and the cDAQ.  I would try unplugging the laptop from the wall to see if that changes the behavior.  When the laptop is unplugged it should be floating and its ground level should be pulled pretty close to the cDAQ.  If it is plugged in and the power supply for either the laptop or cDAQ is wierd different offsets could be introduced to the ground plain of the computer and cause a ground loop over the shield of the usb cable.  I could imagine that could cause strange issues like this.  As an analog power issue I would not be surprised if it was intermittant.

If you are still in the San Clemente location you could try different power configurations and see if you can reproduce it.  Try plugging the laptop into a different outlet from the cDAQ, try running with the laptop plugged in or not, etc.  You might be able to reproduce the issue and then know how to resolve it when you move to the Bay area lab.

Hopefully some of these suggestions are helpful.  Let us know how the debugging goes.

Regards,

Neil S.

[vsun]

Hi

When its not working, when we plug it into the computer, the cDAQ shows on MAX but its blanked out with a little "x" icon. I think those are just saved icons there.

We tried deleting that device in MAX in the hopes when we plugged it in it would reset itself. But the device never appeared after deleting it when we were up north. When we got to San Clemente and plugged the cDAQ to the computer, it then created the device again.

When in the Bay area, I checked the device manager and it shows the device connected to USB.

The Ready and Power LEDs are lit up on the cDAQ.

I think it does connect with the computer, because you can see the MAX window automatically refresh when its plugged in, but it just shows the device as blanked out.

There are no differences in how the 9174 is wired up. In fact we even tried with the 9174 not wired up, and the analog inputs were not connected to anything. We just wanted to see if the cDAQ could connect to the computer. Knowing we had this problem before, we even wrote down and followed the same plug in and power up procedure we did at San Clemente, but it didn't work. We have tried with the laptop plugged in and unplugged in the Bay area and it never worked, and we tried with the laptop plugged and unplugged in San clemente and it always worked.

In the Bay area, we tried it connected and not connected to the wifi and at san fran airport I was connected to the wifi. And it didn't work any of those times. We tried to reproduce the problem in san clemente by not connecting to the internet (turned off wifi), but it still worked.

Regarding outlets, while in the Bay area when the cDAQ didn't work, we tried the ground fault outlets (in the lab spaces) and normal outlets (in the hallway). It never worked. In the airport I'm sure they have current limited outlets in the terminal, but the cDAQ didn't work either. In San Clemente we went around our lab looking for those ground fault outlets (found one in the kitchen and bathroom), but the 9174 still worked.

In frustration we thought maybe when it was in my backpack during the trip from the Bay area back down, it somehow fixed itself. So we tried shaking the cDAQ to reproduce the problem but it still worked fine.

My coworker brought the cDAQ home to San Diego to try to reproduce the problem, thinking the power grid in San Diego is a bit different than San Clemente. I'll keep you updated with her results.

[vsun]

I tested the DAQ, it works at my apartment and at my coworkers in Southern California. I will be going ot Northern California next Monday. Can you please offer suggestions of tests I can run if it doesn't work up there?

Thanks

[vsun]

I tested the DAQ in Norcal and it worked there and in diffferent labs. Not sure what the problem was. I spoke to a Labview representative on the phone, he said he's seen sometimes there is a background process that could have gotten turned off which results in the DAQ not being detected.

[vsun · Accepted solution]

Ok I believe I have figured out why it didn't work.

I plugged in the DAQ today and noticed I was having ths same issues as before, it was not communicating with my laptop. The labview programs designed for it were not working. I remember talking to a Labview representative over the phone and he said sometimes the background services get turned off. So I went looking and found a service called "NI Device Loader" was stopped. The executable is called nipalsm.exe.

I restarted the service and replugged in my DAQ and it was working again!

I believe with this service stopped, the computer doesn't load drivers for the DAQ so it won't work.

I was able to reproduce the problem by stopping the service and trying to run my labview programs, encountering the same errors I had in Norcal. And I fixed the problem by restarting the service.

We had tried restarting our computer to fix the problem, but I guess this service doesn't get started sometimes when the computer reboots.

[Knoxberry]

I'm glad you were able to discover the issue. For future reference, if NI Device Loader doesn't start properly, you can set it to restart automatically by right clicking NI Device Loader and going to Properties>>Recovery.