usbser.sys on Windows 7 Embedded, installed but not found

Question

I've installed a barcode reader on a Windows 7 machine: it is configurated with virtual serial port mode.
At the initial moment the driver was not found; looking in the Windows folders I did not find the usbser.sys file.
So I installed the following package:

pkgmgr /ip /m:winemb-inf-mdmcpq.cab

Looking in the Windows folders now I find the usbser.sys in a couple of locations such as System32\DriverStore\FileRepository... and winsxs... folders.
Still the driver for the barcode reader is not found.
I took a look inside the device and it has as compatible IDs:

USB\Class_02&SubClass_02&Prot_01
USB\Class_02&SubClass_02
USB\Class_02

Is it not sufficient to try to locate the usbser.sys driver?

Answer 1

I solved writing a inf file where I specified the USB VID and PID of the device.
In this way the serial driver was loaded and a port number was assigned.