Cdaq9172 random disconnect

[Tui]

We have a Cdaq9172 unit connected via USB to the PC running Labview V8.5.  Currently connected via a 5 m USB extension cable to PC.  

Problem.  The daq unit looses the connection to the PC at random intervals.  To fix we need to remove USB cable and plug back into PC.  The problem can be once a week, once a day or several times an hour.

The environment is a sawmill, but the PC and CDaq unit is in a computer room.  We have had this problem both with Windows XP and a new Windows 7 64 bit PC

On the old PC we often had to reboot the PC to reestablish connection so I assumed the USB control on the PC was the problem while with the new PC we just needs to unplug/plug in the USB cable.

Any suggestions? 

[CsabaF]

I had similar problems with one of our cDAQ systems used in a test setup.  There are quite a few huge pumps running close to the test setup and once in a while the communication to the cDAQ chassis got lost. 

The root cause was the length of the USB cable from the PC to the cDAQ. It has been working since I replaced the original 5 meter cable with a much shorter one (ca. 1 meter). (Edit: of course the root cause is not the lenght of the cable, but the noise generated by the  pumps and picked up by the long cable)

Try to move the cDAQ abd the PC closer to each other and use shorter cable if possible.

[Akardo14]

Hello Tui,

I think the suggestions given by CsabaF are quite accurate and you should try them. Please do post on the forum the result of doing those tests.

Juan B.

National Instruments.

[Tui]

Thank you. I have advised our customer to do as you suggested

We do have 2 other installs where this problem does not occur, in both cases we do not use the USB extention cable

[Hooovahh]

I got one.  The USB cable that comes with the cDAQ chassis has magnets on the ends to help with noise.  Once someone grabbed just a normal USB cable instead of the one that came with the chassis.  It would work in a noisy environment most of the time, but it would also disconnect once in a while.

At the time we didn't have much time to debug, so we bought a cDAQ ethernet chassis instead and had no issues with it.

[JÞB]

and check the power management options on the USB hub operating system be shutting off the USB power?