Need to cycle the USB connection to a DUT

[rsmrostov]

This is a difficult one:

We have a test rack, that has two 12-port usb-hubs feeding the trip-lite usb-to ethernet extenssion cables..  Total of 24 UUTs are bieng tested asynchronously via test-stand sequence.  At the end of each sequence the device is put to sleep.  The goal of this test is to wake it up from the sleep mode and confirm that it wakes up.  The only way of accomplishing this so far is to physically reconnecting the usb to the device (disconnect - then - reconnect)

I want to be able to do this programmatically: the only way I could think of ad-hoc is to design an adapter board which will trip the D+ (and D- as well?) line with a relay.  Obviously some code to confirm that a device has remaped to the same COM port it was assigned earlier would be needed as well.

Can someone

a) confirm this will be idencticaly to disconnecting the usb mannually

b) point me to a possible existing solution where one can remotely enable/disable ports on a usb hub

c) have other ideas to throw my way.

Thanks for the help and let me know if more details help.

[Michael_78]

I have had a similar situation before. I had success by using a relay to open the 5v line but I eventually found a software solution. There is a command line tool in windows, devcon.exe. I used this to delete/reinstate the driver which worked quite well for me. Maybe it is worth a try for you, but it is not exactly an elegant solution.
Michael.

[mikeporter]

This definitely would fall into category C, but I can't help wondering why you are messing with USB/serial/converters when the DUTs have Ethernet interfaces.

Mike...

[rsmrostov]

Michael, thanks for the advice.

The thing is - I am using the usb hub to ethernet - usb extension, this would kill the rest of 11 UUTs on the hub as well, or could you target individual COMports?  may be disable/enable the device?  I am just not sure, what the effect will be with the ethernet extensions and a 1-to-12 usb hub....

[rsmrostov]

Thanks for answering my post:

The UUTs do NOT have the ethernet plug, they only have a usb plug.  The reason we use ethernet extensions on the rack is the distance ~20 ft (beyond USB's spec).  Before it used to be just USB cabling and we had all sorts of problems.

so the connection is PC (or PXI depending on the rack) -> usb (1->12) hub -> to ethernet usb extension -> back to the usb into the UUT.

[Michael_78]

Ok, i have had a look at my devcon code.

first, you need devcon.exe for 32 or 64 bit windows, they are different.

'devcon rescan' does the same as f5 in device manager

'devcon find *something*' returns all installed devices with the text 'something' in the device id.  you can use this to find the device you want to remove.

'devcon remove myDevice' will uninstall myDevice.

I know this is sketchy help, but hopefully it will get you going if you want to explore this option.  It may work for you, even with the usb-ethernet adapter.  All i can say is try it and see how you get on.

Michael. 

[PhillipBrooks]

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@rsmrostov wrote:

The UUTs do NOT have the ethernet plug, they only have a usb plug.  The reason we use ethernet extensions on the rack is the distance ~20 ft (beyond USB's spec).  Before it used to be just USB cabling and we had all sorts of problems.

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Never used this, but I  had bookmarked it a while back specifically for this issue:

http://www.corning.com/opcomm/OpticalCablesbyCorning/products/USB-3.Optical.aspx#.VWxOpdJVhBc

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USB 3.Optical™ Cables by Corning connects computers and devices at incredible speed and over longer distances. They’re thin, light and remarkably tough — Optical Cables by Corning can be bent, squeezed, and tangled.

Connection Diagram

Available in 10m, 15m, 30m, and 50m lengths.

[rsmrostov]

Thanks Phillip, I will take note.  The price is quite serious, having (24 uuts / rack * 6racks)*~180/uut is up there.  The trip lite ethernet extension is ~$30, ethernet 25ft cable is ~5.

However, I am looking for a certain way of cycling the power over USB connection.

[rsmrostov]

Michael, thanks again, I will take note.

However, having a powered 1-to-12 USB hub along the way will still provide power to whatever is connected to it all the time.  And I can't disable the whole hub, because there are possibly 11 devices on that hub being controled through it.

[PhillipBrooks]

So it seems that the USB standard requires a feature called PPPS (per-port power switching), but most  (if not all) hubs don't provide the extra components to enable this feature.

http://hackaday.com/2014/02/05/software-controlled-per-port-power-switching-for-usb-hubs/