Communications Failure


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I have a test stand with instrumentation read by a Labjack U3. I keep getting the following error:

D005:02:1008

Device #2 error: Communications failure

This seems to happen every 2-3 days (I'm running 24/7). What can cause such errors and what can I do to solve (or at least ameliorate) this problem?

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I'm afraid you'll have to ask the folks at LabJack why this error would come up. It is an error returned by their UD driver. My guess is you have some sort of USB glitch, perhaps caused by another device on the USB port, but as I said, ask them (www.labjack.com)

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I guess my real question is: how do I respond to such an error. I can trap it just fine using OnAlert(). If I notice these errors coming in each read, is there something I can do in code to fix things? What commands can I try to issue?

Since shutting down and restarting DAQFactory Express appears to be the only thing that fixes this problem, what else can I try in code? I've tried manually entering Safe Mode and then leaving Safe Mode, but this doesn't fix the problem either.

Any help is greatly appreciated.

-Matt

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Do you continually get comm errors once the first one appears? Does the labjack basically go offline until you restart DF? Did you talk to LabJack to find out why you might be getting comm errors in the first place? Until you know the cause, its kind of hard to write code to recover from it. I believe there is a reboot function available from the UD to reboot the labjack. That would be one possible solution, but I don't know. LabJack's and DF don't just give comm errors after 2 days without some sort of external cause (or a defective labjack)

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Sometimes DF recovers just fine on its own. That only seems to happen if the error occurs only occasionally. If the error starts coming in each read, then its a foregone conclusion that it won't recover. LJ said that it seemed like an application or driver issue, but I don't know how I would find out which (or what I would do if it was either).

What does DF do when you open a .CTL file? What are the commands it sends to the U3, and can I send those commands in a sequence? Similarly, what does DF do when it shuts down? If I can't communicate with the U3, are there any commands that actually get sent out to the U3 upon shutdown (even if they aren't received)? Are there things I can do to disconnect from the driver, and then reconnect?

Thanks,

Matt

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Yes LabJack pointed me to your post on their site. Are you streaming?

DF doesn't do anything when you open the .ctl doc. It used to if you used the quick -device configuration on the labjack, but that's been largely disabled for a couple years, so unless you are running a really old doc, nothing will happen. Of course any Auto-start sequence with script you wrote would execute.

DF also doesn't do anything on shutdown.

In fact, DF doesn't really do anything but pass 99% of the commands directly through to the LabJack UD driver. We designed it that way so that LabJack could add new features to their devices (which they do often) without us constantly having to update our driver. So, if the problem is driver related it is likely in the UD. However, if you could post, or email your .ctl doc, I can take a peak to see if you are doing something that we do extra processing on.

You might try using the resetlabjack() function and see if that fixes it. From your other post you said only a restart fixes it, so I doubt this will do it, but its worth a try. If you have a using() command in place, then its just ResetLabJack(ID) where ID is the id of your labjack.

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  • 2 months later...
  • 2 years later...

Reviving an old topic...

I have a similar problem with a rig which performs cyclic motion tests on metal specimens.

Tests are run continuously over the course of a few days. However, after a random number of cycles, a LabJack Communications Failure would occur, seeming to hang DAQFactory. The control knobs and components on the GUI were unresponsive. Restarting DAQFactory did not reset the U3. The only solution was to power cycle the U3-HV.

The first time this occurred, it was suspected to be due to a timing lag, so streaming mode was implemented. However, the problem is still present.

What could be the cause of this communications failure error?

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All the communications is done in the LabJack UD driver, not in DF, so the issue must be there. So, either you are running an old version and need to update the UD and your firmware, or there is a bug in the UD, or the latest UD has changed in some way that it isn't working properly with DF. I'd start with the first, and will let LabJack chime in on the other two and maybe other concerns, as it could also, be a USB issue.

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