Use as com port with Windows 10

[onerng]

For what I want to do a com port under Windows 10 would be fine.
Sadly onerng.inf is unsigned and will not install normally. Rebooting Win 10 in allow unsigned drivers lets the inf install and the onerng now shows as USB Serial Device (Com3) instead of Communications Port (Com3) but doesn't respond to any comms package I have. 
The hardware IDs match the inf.
The driver is now usbser.sys as the inf wants.
This possibly means I have the settings wrong. By reading the source and TI user manual I reckon it is running at 9600 baud, but cannot confirm what if any flow control is being used.
Any suggestions for things to try?