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Windows 7: USB Driver installs with port expander but not directly into main USB

18 Oct 2016   #1

Windows 7 Professional 64 bit
USB Driver installs with port expander but not directly into main USB

I have a device which I'm having trouble installing the drivers reliably. It is a Siglent power supply and does not have any associated drivers from the manufacturer. It tries to install as a USB Test and Measurement Device which I think calls the ausbtmc.sys in the c:\windows\system32\drivers. This is all well and good and works fine if I do this using the USB Port expander...but if I try plugging the devices in directly, the driver can not installed. The device works just fine when using this driver, but I'm just at a loss as to why I can't point it to this driver directly when it comes up as an 'unkown device'. When I try to point it directly to...

C:\Windows\System32\DriverStore\FileRepository\ausbtmc.inf_amd64_neutral_cb428e1310c01373\ f

C:\Program Files\IVI Foundation\VISA\IVI USB Staging\b841aa80\Windows


and maybe one or two other places as well where this driver might exist. I either get a message saying windows found the best driver "unkown device" and installs it. Or I get an error saying..."doesn't contain a compatible software driver...make sure it is designed to work with Windows for x64-based systems."

I've even connected a new (never connected before) device and the same problem exists. Windows will find the driver and install it automatically from the port expander slots, but fails to install it when plugged directly into the PC.

I have been able to connect this device through a port expander which I need to use because I have a lot of devices connected. I've gone through a few forum threads where they talk about un-hiding unconnected devices in the device manager and removing them. Also removing /System32/DriverStore/infcache.1 and other related files in that directory. The instructions talk about removing ALL USB drivers, but this is not possible because the only access I have to this computer is through a usb mouse and keyboard. I did TRY to uninstall the ports and the mouse/keyboard shut down. I then did a hard power off and on. This did not change the strange behavior.

I've been uninstalling/removing files/updating software for the last two days now with no success. I even reverted the system back as far as I could go to see if that would help. All attempts have left me with only being able to install the devices through the expander.
In a nutshell, why would windows be fine with installing a driver when plugged into the port expander, but NOT when plugged directly into the PC?

My System SpecsSystem Spec
19 Oct 2016   #2

Windows 10 Pro x64, Windows 8.1 Pro x64, Windows 7 Ultimate x64 SP1,

Hi and welcome.

Is it possible that the device is loading down the USB port when directly connected?
Does the manufacturer have any recommendations regarding USB?
My System SpecsSystem Spec
19 Oct 2016   #3

Windows 7 Professional 64 bit

I guess that this is possible. The USB hub that I am using is a powered hub. And interestingly my IT guy enabled some port setting on the PC that enables the power to the port at all times. This seemed to fix the problem...once. I witnessed that the device was recognized directly on the PC's usb port. However, I then plugged a second device identical device in and it was unrecognized. The computer went right back to not being able to find the driver.

I also used an unpowered usb hub...a real generic piece of hardware...and it worked perfectly. Go figure. So it seemed for a moment that power might have been the problem. So I'm back to square one. Why can't I directly tell it what driver to use when it clearly CAN when connected to the hub?
My System SpecsSystem Spec


 USB Driver installs with port expander but not directly into main USB

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