Re: [CAD_CAM_EDM_DRO] 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

Graham,
Its not rocket science. Just treat it as a switch. Not a good switch
perhaps. The contact materials are chosen for their mechanical properties
not their electrical properties. Check the values you get with an ohmeter
you will find that the rest state value may be as high as 1Kohms, it
depends on how much use it has had and how old it is. In order to preserve
the contacts as long as possible keep the current from your interface to
about 0.5mA and do not exceed 12V open circuit voltage. The standard that
Renishaw use is a 12V supply with a 22Kohm series resistor. However 9V will
suffice if you want to operate on a PP3 battery. Because of the poor
contact resistance you will need to use a comparator to sense the operating
state. Set this at around 1.5V for lowest pre-travel but up to half the
supply rail if you are not too worried about the last 0.1micron! A slow
comparator is best with some hysterisis to remove some of the contact
noise. If you are feeding this signal on to a computer etc then further
filtering will be required but if you are just using it to drive the LED
then the comparator output will be fine. Make sure that you keep the
current to the LED below 20mA. I can't remember if the PH6 has a series
resistor so better assume it doesn't.
Hope this helps and you find the probe is useful.

Regards
Bill Phillips
Stroud
(Electronics designer Renishaw)