Ok, so I'm gonna use this thread almost as a diary of how I get on trying things on the described system.After some useful advice from EposWizard;
As for the software, I only ever used PLM2000 in my engineer days so have no experience of Unilite, I'm sure it will be pretty much the same though. If you make the cable up and connect to the till, you can try to RECEIVE the info from the till first so you have a backup.
You cant really do any harm by plugging it in, it's pretty self explanitory really, ideally you would receive all programming in, then you can change it, edit things etc and then you send the changes back.
I have bust out the soldering iron and a fresh D9 serial cable in preperation for plugging a laptop running PLM2000 into the serial port of the TX-870, but first I need to change the pinout of a standard cable to make it match the spec of the Uniwell specific cable; (see post below)
http://www.eposwizard.co.uk/uniwell-plm-2000-communications-cable-spec-t629.htmlSo far I've painstakingly removed the plastic coating around the internal wires at the female connector end and made up a diagram of where they originally connected to so that I know what came from where. This will allow me to swap them to the necessary positions. I have also used the soldering iron to clear any trace amounts of the old copper cable from the old pin connections so that the female connector is clean and ready to have the small wires re-attached. Pics to follow.