In preparing to do this I have read much about the chips, RS485, and analysers/decoders that are out there. I am getting close to purchasing a USB to RS485 adapter and software to use it with - but have been unable to find critical information specific to my situation:
My desktop computer is negative grounded and the device is positive grounded.
I don't have a laptop that can be used for this purpose (which I have read could be used if it wasn't plugged into mains when connected to the fixture.)
Stuck with just the desktop to use, it seems to mean I'll just short it all out if I connect the grounds - possibly damaging the fixture, my desktop, the adapter, or any combo of these.
How do you properly set up for reading the signals with a -GND desktop and the +GND device?