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USB-6501 static problems

We are using the OEM version of this board for embedded instrument control.  We've seen some problems where static discharge on the instrument chassis leads to the board giving error -50405.  After this occurrs the board must be completely disconnected and reconnected before it will function properly.

Looking at the board, we find that the USB connector shield floats with respect to signal ground, but that there are several unfilled components which could be used to bypass the shielding to ground (e.g., C1, R23, F1).

Has anyone else seen static problems with this board, and if so what/how are you dealing with it?

Thanks in advance!

James Brunner
Summitek Instruments
Message 1 of 16
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Hi James,

I did a quick search of customer issues and haven't come across anything similar. Is the instrument chassis connected to the 6501 gound or other pins in any way? How have you determined that it is a static discharge is causing this behavior?

Andrew S

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Andrew -
Thanks for the reply.  Our instrument chassis was generally isolated from any ground connections on the 6501 board when we were experiencing the static problems.  This was not our design intent, but we found production using plastic standoffs to mount the assembly to the chassis instead of metal.  Upon further investigation we found that the USB connector shell was also isolated from signal grounds on the 6501.

We determined it was a static discharge basically emprically by running the system, rubbing our feet on the carpeted floor, then touching the instrument chassis to get a static discharge.  This lead pretty uniformly to the error -50405 I previously mentioned, and not being able to reset or use the 6501 until complete disconnect-reconnect cycle.

We have found that connecting the 6501 signal ground to chassis via the metal mounting standoffs has probably eliminated the problem, however, we are left with some uncertainty, thus my posting.

Again, thanks, and we're also interested to hear from anyone else out there.

James Brunner
Summitek Instruments
Message 3 of 16
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Hi,

I too, are having an issue with this 50405 error code.  My test setup is such:  PC going to a USB hub.  A UUT is then connected to the USB hub, along with the USB-6501.  With this setup, as soon as I toggle my UUT thru USB, the 6501 would drop out, giving me a 50405 error.  As you mention, I have to unplug the 6501 in order to reset it.  What's even more curious is that this only happen when I use a Dell PC, but works perfectly fine when I have my test bed setup with a HP PC.

What exactly is the 50405 error code means anyway?  Is it as James had mention, not enough grounding?

 

Thanks,

Message 4 of 16
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Hi Zebraman,

 Here are some thoughts with regards to your questions.


ERROR 50405:

Under normal circumstances your USB device should not stop responding during acquisition.

Error 50405 simply indicates that a device you have plugged into a into a USB 2.0 host controller has lost its connection.  The common reasons this occurs are:

  • You unplug or insert a second device


    You lose power to the device (from hub (is your hub powered?) or PC)

Improper grounding leading to a static discharge could also cause this behavior. It is always a good idea to ensure proper  grounding of all  components in the system.

 

SUGGESTIONS WHY ONE PC WORKS AND ONE DOESN’T:

The southbridge or I/O controller hub (ICH) is responsible for USB communication for your PC. Making or breaking another USB connection while your data acquisition device is connected may cause a communication error. This has been observed on chipsets with ICH versions 2, 4 and 6, but may affect others as well.

To determine the chipset in your PC, you can find it listed in the Windows Device Manager or in your motherboard's BIOS. If you know you have an Intel processor, Intel also provides a Chipset Identification Utility that you can download to identify what chipset your motherboard has.

If your application requires plugging/unplugging of USB devices and your PC has one of these ICH versions, a quality powered hub connected to USB 2.0 may help. Alternatively, consider using a PC with a different chipset. If you are using a laptop computer, check your power settings to make sure that the USB ports are not being turned off to conserve power.

 


You might also check out this forum:

USB 6501 card(s) becomes unresponsive


Jared T.
Message 5 of 16
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Hi Jared,

 

Thanks for the info.  This morning I ran my test setup again, but this time with a 1.0 hub.  Magically, my problem goes away.  After that, I decided to disable the USB 2.0 driver, and went back to a 2.0 hub.  My test setup still works.  This agreed with what you had said, because I look up the chipset, and they are the ICH version.  Looks like my UUT is not a true 2.0 device, and thus cause the USB-6501 to loose its connection.

My current hub is a powered unit, but I won't call it a quality unit.  What would you suggest as a quality USB 2.0 hub?  Please advise.

 

Thanks for the link as well.   Got a lot of info out that that too.

 

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I was glad to hear that you found the likely cause of the problem.  Unfortunately, I don’t have a good recommendation for a model and manufacturer of a quality USB hub. While the USB protocol is a standard, it is open enough that quality differences can be seen between companies that loosely follow the standard and companies that really push for strictly adherence.  I would suggest following the age old advice that “you get what you pay for.”  If it were me, I would look for a manufacturer that has a reputation in the business for quality.

If anyone else has any specific recommendations, please feel free to post them.

Jared T.
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I have been having some trouble with a similar NI USB device.  I had 2 devices going into a 4 port hub and one of the devices kept giving me the -50405 error.  I finally found that it was the usb cable between the hub and the computer that was messing everything up.  I switched to a new USB cable and everything works now.

I'm not sure what the difference in USB cables is, but I just used a brand new one that I bought.

 

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Hey,
 
Thanks for posting! You mentioned the old cable was messing eveything up - was this the cable that shipped with the USB-6501 or just one you happened to be using? If it was the one that shipped with the device - was there anything written on it (serial/part number)?
 
If it is one of ours I'll try to look into it some more.
 
Andrew S.
 
Multifunction DAQ Product Support Engineer


Message Edited by stilly32 on 05-16-2008 12:57 PM
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No, this was a cable that I had in my lab because I needed a longer cable than what came with the USB device.  I bought a new cable from CDW that now seems to work well.  
 
I have 2 separate boxes each with 2 USB devices hooked up to a linksys 4 port hub.
The procedure I used to load my devices was as follows: 
I powered the first box and installed the drivers and used the self test button in Measurement and Automation.
Then I rebooted the computer and checked to make sure the devices were still there and working
Then I powered the second box and repeated the self test and reboot procedure.

I'm not sure if this actually makes a difference because I was still getting the error message when I was using the old cable.
But when I switched to the new cable everything is fine.
 
Hope this helps.

 
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