Although I hadn't mentioned it I had tried it on a different input on the same module but not a different module.

One of my modules with spare inputs is tucked away in another part of the house and nowhere near node 0.

This is the interesting bit; when I had it connected to the previous module the 12v to the PIR was connected to a separate 12v power supply as are all the PIR's. In the remote location I don't have access to this power supply so I pinched the 12v from the Idranet connector. My wiring sequence was, and this is important to note, to connect the 0v and input connections to the PIR and then the positive and then the negative. After I had connected the positive I dropped the screwdriver and of course it rolled under something. I retrieved my screwdriver and imagine my surprise when I stood up to find the PIR working without the negative connected. I connected it anyway as one should and it worked flawlessly with the voltages dropping from 3.2v to 47mv. I reconnected back to the original module and used the power from that module's Idranet connector and its working perfectly.

- Neil