8451 lock ups

[Cimteker]

Hi,

I am using NI-8451 to communicate to a battery emulator (q20z80 Fuel Gauge). Every couple of hours it locks up. The LED goes off and all communication fails.

It also disappears from the list of available device seen through NI MAX. Computer soft reset does not help, hard reset or unplugging USB cable does.

There was another thread here related to a similar problem but I don't think the solution was found. I do not have any control over the frequency of messages that are being sent between the DUT and the battery emulator. Here's the thread.

http://forums.ni.com/ni/board/message?board.id=170&message.id=319634&query.id=495330#M319634 

I am running 2.8 GHz Intel Core2Duo with Windows XP SP3. 

Thanks

CT 

[lab_boy]

Hey,

It seems like the device is drawing more current than the USB port can provide hence it is droping out. Can you try it on different port, or try it on another machine.

Good luck

lab

[JÞB]

Hi CT!

This does seem to be a common problem!  I've seen it myself and have had some luck fixing the problem.

My experiences have led me to the working hypothisis that "not all USB ports are created equal."   It seems that the reliability of the USB connection is effected by the design of its power source.  Some PC power supplies are just not up to the task of powering a DAQ device.  My work-oaroud for this has been to ALWAYS use a self-powered external USB hub that specifies at least 500mA per port.  My favorite USB hubs are made by Belkin - they just seem to work reliably.  This is one of the times that you can't shop by price- read the spec sheets and buy the premium devices. 

HINT (the PC manufacturer sourced the internal hardware on price after all, how many users will really need a top-quality USB port?)

[Cimteker]

Thnaks all for responses.

I will give external hub a try.

CT.

[Cimteker]

Well, I tried D-Link 8 port hub with 3.5 A PS and it actually made it worse. Now when it fails, I get OS message that my USB device is not working properly and I need to reboot the machine. Previously it was enough to remove and restore USB connection.

Any ideas welcome.

Thanks

CT