usb connections drop out

[Jeff.Boeker]

Periodically, say every 100 hours or so all of the USB serial ports we are using will disappear from the NI Explorer (and all the USB DAQ boards will have an error state).  I assume this is happening because the USB signal dropped out somehow -- if I unplug/plugin the USB cable to the computer all the connections will reappear in the NI Explorer.  So the possible culprits includes the OS (Windows XP), the USB cable, the USB hub, or the USB board.  Another possiblity is this is NI's bug (I'll check the device manager next time to correlate). 

Does anybody have any experience this problem and can recommend a possible solution or suggest a test?

Thanks,

Jeff

[Anna_M]

Hi Jeff,

I was wondering - what USB Serial device are you using - is it one of our USB 232 devices, etc? 

On your computer, does Windows have the USB power save option turned on - we might try disabling this and see how that works.

Also, I am guessing you are doing data acquisition or other communication on several if not all ports during those 100 or so hours before the connection is dropped.  Do you have anything connected to those ports powered with an external power supply? 

[Jeff.Boeker]

Hello Anna,

I turned off all power saving on the pc in general and I also individually disallowed all USB Root Hubs from being able to be turned off to save power.

You are correct that I ame communicating with multiple ports at all times before the connection is dropped.  There is a USB to serial hub that has an external power supply, also a USB hub that has an external power supply.

Thanks,

Jeff

[Anna_M]

Hi Jeff,

I have seen instances before where externally powered components in the system whose power supplies were acting up could cause this sort of behavior - could you verify that you power supplies are behaving normally - do you have any other supplies with which to exchange them? Or alternatively, is there any USB device on that hub that seems to be linked with the dropping of the signals?  To take it a step further - does the link drop when you only have the hub connected?