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Damaged ability to Stream?


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#1 ljpark

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Posted 04 January 2013 - 07:56 PM

Hi all, I managed to accidentally create a short between signal ground and my logic +3.3 V line for an undetermined period of time (I believe it was fairly short, ha ha, but I can't be sure of this). Would this be enough to cause the streaming function of the labjack U3 to become damaged? More context: I'm using DAQFactory to collect data from a U6 and two U3's (one LV and one HV). In the past, I've been able to stream data from the U3 without any issues. For my new application, I wanted to stream simultaneously from all three units. While testing out the functionality, I was able to get the U6 to stream, but for some reason was unable to get the U3's to stream at the same time. After thinking it was only a software issue, I was moving things around on my board when I saw there was a power/gnd short. I'm not sure how long it had been there or whether it had been there the entire time of my testing. However, now I'm unable to stream from the U3's at all, even when running test programs for streaming solely on the U3's. I've even run LJStream with the U3's and am getting an error that no data was received (Error 58, stream timeout). The weird thing is that the command/response appears to still be working fine on both U3 units, and the U6 appears undamaged (is able to stream fine) even though it was connected to the same shorted ground. So, now I believe it's a purely hardware issue with the U3's, but it seems strange to me that just the streaming functionality would become damaged rather than the entire unit. Also, does this mean the U6 has more protection against shorts? I was wondering whether this made sense (and if other users/labjack support had seen similar cases) or whether there's something else going on that i need to look into. Any insights would be greatly appreciated! Thanks!

#2 LabJack Support

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Posted 06 January 2013 - 11:14 AM

A short from a digital I/O will not cause damage. In fact, you can short any I/O to any other I/O without damage, even VS to GND should be protected.

Test with no I/O connections to the U3 at all, just USB.

Make sure only a single device is connected and try testing stream functionality with LJStreamUD.

Try using LJSelfUpgrade to update the U3s with new firmware, even if it is the same version you already have. I would try V1.44 or beta V1.55.

Are you running driver V3.25:

http://labjack.com/support/windows-ud

You could see if an update to V3.31 makes a difference.

#3 ljpark

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Posted 08 January 2013 - 01:02 AM

Thanks for the quick response - I just tried testing with no I/O connections and a single device (U3-HV) with LJStreamUD, and got the same "no data" error. I've also tried reinstalling v1.44 which didn't fix the issue. I looked for beta firmware 1.55 but only found 1.45 (http://labjack.com/s...irmware/u3/beta), which I also tried without success unfortunately. I am running driver v3.25, but am hesitant to try upgrading to v3.31, since the U6 is working fine and I'm able to get by without streaming on the U3's for now. I know it's a little superstitious, and if you really think trying v3.31 could solve my streaming problem I can be convinced, but at this point, I'd rather not take that small risk that it could mess something up. Also, for clarification on what occurred, it wasn't a short from one connection on the U3 to another. The short occurred between a +3.3 V power rail (supplied by a voltage regulator converting 5V to 3.3V) on a breadboard to it's neighboring ground rail. The U3's SGND was connected to that ground rail on the breadboard, so it experienced a 3.3V short from a separate power source unconnected to the U3 except through the short. Not sure if this makes a difference in the protection in the U3. Anyways, I already have another U6 on the way - the project is pretty time sensitive - so this issue may be put on the backburner for when I have more time to deal with it. Not sure what the cost is to get these units looked at if I can't figure out what's going on, but perhaps that could be emailed to me separately. Much thanks!

#4 LabJack Support

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Posted 09 January 2013 - 08:42 AM

I really can't think of a damage mode on the U3 where everything works except stream mode. Anyway, I would test on a different computer with V3.25, and if you still see the problem try updating that computer to V3.31. Another thing to try is different cable, different hub, and no hub. If you still see the problem contact [email protected] for an RMA to send the U3 back to us.


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