Using Multiple USB DAQ

[mhennggo]

Hi,

Good Day!

I just built a test system which comprise of several USB DAQ's ( 3xusb6501; 1xusb6009; 1xusb dmm 4065). Without using a USB HUB, I connected all five of them directly into. the usb port of my PC. It seemed to work well when i am running the VI's alone but when i put them into sequence in TESTSTAND I'm kinda having a problem at run time.

It will Intermittently pass/fail and then the pc will popout a message that "It has detected USB-6501" 

My PC properties: i5 CPU, 3.19GHZ, 2Gb RAM, 32-bit, Windows 7 Pro

Software : Labview 2013, Teststand 2012

I checked and I believe that I am not having any loose connection.

Is there a known issue regarding the use of multiple daq in a system?

Any idea or suggestion to resolve or further check my system?

thanks in advance.

menggo

[SnowMule]

Using multiple DAQs on one system is fine.  Done it many times before.

There's something on the USB system that's causing an interrupt or reset, that's why you're seeing the driver reload. 

Could be caused by:

• Connection/disconnection of another device on the root hub
• Power surge or short-circuit causing a shutdown/reinit of the USB device
• Power management system on the PC shutting down ports

Check the currents in and out of the DAQs, make sure they're within USB spec for USB-powered devices.  If you're using a hub, make sure it's external/"self"-powered.  Check your circuits to see if there's anything causing unusual current spikes on the inputs (Inductive kickback on relay/solenoid coils, for example).