USB Hub Problems

[jon_mcbee]

We need to use a USB 6501 digital IO and a USB 6525 relay board but only want to have one USB cable running back to the computer.  For this application a USB Hub seems to make sense but I wanted to poll the NI audience and see if anyone has had any issues with using a USB hub to control to USB DAQ boards.  Any info at all will be greatly appreciated.

Cheers!

[Ben]

Three suggestions come to mind.

1) Make sure the hub is USB-2 since there is a big difference in speed.

2) Watch your power req's if the USB devices get their power from the USB.

3) Don't be suprised if you disconnect reconnect the hub and the device ID's change.

Ben

[jon_mcbee]

I hadnt considered the fact that device ID's may change with a disconnect.  Do you think that a vi like the one attached will solve this problem?

Cheers!

[samantham · Accepted solution]

Hello,

Yes, the code you posted should help if the devices get renamed.  Ben was right to mention power requirements for the USB hub.  Attached is a KnowledgeBase that recommends self-powered instead of bus-powered hubs.

AE KB 22492O8F: Why Will USB-Based Devices Not Run on Bus-Powered Hubs?

[jon_mcbee]

Thank you very much for the link, I found it very useful!

Cheers

[astroboy]

Hi Ben,

You mention 1) Make sure the hub is USB-2 since there is a big difference in speed.

I have a problem

I have a non-NI device (ie, meter reader) by USB to Serial Bridge and NI USB-6220 together with USB Hub (2.0). Will that be a problem?

I tried using NI MAX and can see comport and USB 6220. However,  either one will give error during the manipulation like send, receive, activate controls.

Please advise

Clement

Message Edited by astroboy on 10-06-2008 09:17 PM

[samantham]

Hello,

I found some more detailed information in this KB about NI-USB devices with USB 2.0.  I hope this helps, however it seems the problem is related to the hub or the other device.  Please do some testing with the NI-USB to limit to cause.  Does the NI-USB device work on the hub without any other USB device?  Is the hub externally powered?