This is in danger of getting VERY confusing as we have two OPs asking similar questions. I have posted a suggestion to Ian which should work, based on my experience upgrading both a lathe and mill from PP to USB using UC100s. I agree that the USB connection Ian has is probably for power - the BoB on my lathe requires this as well as the UC100 for "data" but the one on the mill does not.

In reply to Kevin: can I ask why you have installed UGS? And can you please give more details of your system?

You say...

"Physically its a USB laptop connection out, Controller USB in, serial port out, Router is Serial in." I think that means that both your laptop and controller have USB ports which are by definition serial.

I see that at least one CNCEST machine says that its controller needs "G Code" - that may indicate that inside the motion controller uses GRBL on an Arduino (or similar processor). GRBL/Arduino does accept G code commands though needs a lot of other stuff, and programs such as UGS and GRBLController can provide this. So did you install UGS because it was suggested by the supplier? The combination of UGS and GRBL is sort of equivalent to Mach 3 with parallel port. If your controller does use GRBL then I suggest you go to the GRBL and/or UGS forums.

We await more information! And perhaps Kevin, you could start a new thread with your query please?