USB device temporary not recognized when multiple USB devices connected to a laptop

[andrej]

Hi,

I am developing an application, where I have 6 USB devices (two of them are NI DAQ device, NI USB-6343 and NI USB-6210) connected to one laptop. 3 devices are connected via powered USB hub and other 3 devices are connected directly to laptop. This configurations works fine for the most of the time, but sometimes it happens that one device (random one) becomes unrecognized (by Windows) and the application returns an error. The device can be disconnected and connected again in 5 sec, but this is unacceptable for me. It doesn't matter how the devices are connected to laptop (via USB hub or directly). I tested this on 5 different laptops (with win7 and win8). Any ideas what can I do that windows will not disconnect devices randomly?

[NordicViking]

Sorry for not having a solution. I just wanted to say, that we are experiencing the same problem. We, too, have tested it on a couple of laptops and with several devices. It seems to be some low level issue.

One hint: At one time the issue was fixed with using a USB-Hub which was externally powered by a mains adapter. Maybe it has something to do with to little USB-power of laptops...?

[andrej]

What do you mean with "USB-Hub which was externally powered by a mains adapter" - what mains adapter. Thank you!

[NordicViking]

Normally, a USB-Hub is only plugged into the USB-port of the laptop. The electrical power it needs is provided by the Laptop's USB-port. However, there are USB-Hubs which can additionally be powered externally by a mains adapter, just like the mains-adapter/power-supply  you use to re-charge your mobile-phone. This type of USB-Hub is mainly used for hubs the provide MANY new USB-Ports; therefore often an external power-source is needed.

By boss was once trying to get a NI-USB-device working with his (high-end) Lenovo-Laptop. Even with several attempts to re-install MAX/DaqMX and other tweaks it did not work out. He swears, that only after using the mentioned USB-Hub with external power it suddenly worked.

I'm of course not sure, it this was really the root-cause of the problem, but this is how the story was... Hope it might help for you!

[andrej]

I understand. We already use an USB hub with external power supply, but it doesn't help.

[ValkoA]

Dear Andrej,

 there's an issue on Windows 7 where an USB device may intermittently disconnect and reconnect, as a reset command is sent on the bus which can disable the driver. Please try the hotfix located at this page ot see if it helps.

Best Regards:

Andrew Valko

NI Hungary