I'm experimenting with the Heidenhain probe on my TNC355 to map surface contours. (I suspect this is equally applicable to TNC151 and TNC155 and possibly the TNC360 and TNC2500 as well)

In this instance I'm just mapping Z at a matrix of points. I can move to the point, do a TCH touch probe cycle, get the Z value into a Q parameter, and output the value of Q to the serial port for collection on a PC. OK so what's the problem? Well:

The control has an internal parameter set to say how close the probe needs to be before you start the TCH cycle. If you are too far away it errors advising that the probe didn't reach the surface, and the program stops. What I need is some way of exception handling this error condition so that I can move a bit closer and try again, but this is eluding me at present.

Anybody been there and done it and can coach me please ?

Andrew