Sorry if this overlaps with some of the above however I don't fully understand all the previous comments.

If ugreen driver allocates USB port to say LPT3 I think you can map that to LPT1 as follows.

Set up a RAW printer on LPT3. Generic text only, will be fine as the plot commands are just text. Certainly for HPGL.

Share it as say Raw-Printer

Then:
net use lpt1: "\\computername\Raw-Printer" /persistent:yes

Hopefully your app can then print to LPT1 and it will go to LPT3.

I think (99%) this will work on a single computer. If it doesn't you can put the printer on another PC.

Some links and stuff-
Google - change windows printer to lpt1:
https://supportcommunity.zebra.com/s...language=en_US

google - windows raw printer driver
https://qz.io/docs/setting-up-a-raw-printer-in-windows

Easier: What is using LPT1? Nothing? Something that doesn't need to? Delete it and reboot. Plug in USB adapter. It should grab LPT1. Voila, plug-n-pray at its' best!
In this case, we wait and see and don't go making behind the scenes actions that may interfere with normal operations.

Thank you so much for your answers.

I am currently stuck with residing the garage and, for the time being, can only work four or five hours a week. (Part of the reason I am trying to move on to "desk" type activities!) We pinched garage siding to fix the siding on the exposed end of the house two years ago and the neighbours are getting restive as the garage just has tar paper like the poor end of an Appalacihan mining town!

Windows version is Windows 10.
Yes, I can print VisualCadd plans to my Brother laser printer. I never even considered whether it used a raw connection or via Windows. It printed fine to the predecessor inkjets too. Two and three computers ago that would have been via LPT port. I didn't notice any problems when we moved to USB so I might make the assumption that it is via Windows.

Yeah, garage siding projects can really drag, especially when you only get a few hours on weekends. I had a similar “patch job” phase on my own garage after fixing up part of the house, and my neighbours also started hinting it should get done. It’s frustrating not having the energy or time, especially after work, projects like window trim or full reside jobs just sit unfinished. I always worry about weather damage to the frame too, even if it’s just tar paper holding out the rain.

There are local guys, mcd contracting, that some friends used in Ottawa to help move things along faster on siding and exterior fixes. Might be less stressful than dragging it out solo, plus the upfront quotes are pretty easy.