We have a number of receipt printers that we've been using via serial cable. With some new software in the future, I've been moving them from serial to USB and have had no issues. We did have to order about 8 new PCs and I can't get the receipt printers to work on any of them. The printer vendor hasn't been very helpful so I'm kind of stuck. I'm installing the printers the exact same way but when I power them on, Windows is saying it can't recognize the USB device and it's showing as Unknown Device in Devices and Printers and Device Manager. All of the PCs, new and old, are Windows 7 x64. The only thing that's different with the new ones may be the USB ports. They're Dell Optiplex 3040 Micro computers that have 2 - USB Charge ports | 1 - USB smart power on port | 3 - USB 3.0 ports. I believer our old PCs all have USB 2.0 ports, which may be the problem. Doing some research, it appears that the 3040's use xHCI on the USB ports which sometimes cause issues with legacy drivers. Is there a way to disable xHCI and see if that's the issue?
XHCI is XTENSIBLE HOST CONTROLLER INTERFACE aka USB 3.0 You cant disable this unless you don't care if NONE of the USB ports work properly. There is no such thing as making USB2 drivers work with USB3 ports. There is also no support for Skylake and 3RD party USB Serial printers and Drivers here on the Dell Site.
Dell makes Special Windows 7 builds for Skylake. There is NO Downgrade Rights for Home Versions of Windows 10 only the PRO versions. And Dell is not obligated to provide you with downgrade media. There is support for windows 7 on newer dells but its not free.
You must install the eXtensible Host Controller Interface drivers for windows 7 as well as the CHIPSET Drivers for windows 7. Skylake Systems are NOT SUPPORTED with windows 7 by microsoft.
Only WINDOWS 10 is supported.
Otherwise you have to find OLDER Dells and use them.