Renishaw probe users?

I just bought a Renishaw touch probe on Ebay. It is a TP2 5way with
a Ph6 shank. The attached cable is a din plug with 5 pins.

I have found data for the connections, they are positive and
negative for the indicating LED one for the sheilding and two for
the probe circuit.

Putting a meter on the probe connections produced a high resistance
that goes open circuit when the probe tip is touched.

Has anyone else used a Renishaw probe with their own electronics?
Anyone know how best to interface with it, I don't want to destroy
any internal circuitry there might be.

Cheers,

Graham Stabler
Nottingham, UK