I expect to find out soon if the opto-isolator sensor now 10m of alarm signal wire away from the USB digital I/O board works as it used to when 10cm away...  It really should, being essentially a couple of milliamps at most of DC with a few volts of voltage drop available.

I have still to tidy up some cables with trunking and clips, etc, but that's all cosmetic.

I have one spare pair of signal wires and one spare pair of power wires available routed from office down to the batteries, to give me some elbow room for the future.

Rgds