Each axis has a reference mark to enable its zero position to be set. This zero position is nominally at the mid-travel point of the axis - the absolute position of the mark is within ±1.5°.
A microswitch activated by a cam track is used to generate the reference mark; the controller always knows in which direction to travel in order to find the reference point.
To set its zero point, the axis must be driven past the reference mark in a negative direction - see note.
NOTE: A specific procedure must be followed in order for the probe's orientation to be determined. Details of this procedure are given in the PHS1 programmer's guide (Renishaw part number H-1000-6005).
Probe orientation with reference marks nominally at zero: