26 I Operating Instructions
I – 3 Actual Value
I – 3 Actual Value
Datum Setting: Approaching Positions and 
Entering Actual Values
The easiest way to set datum points is to use the POSITIP 880's 
probing functions – regardless of whether you probe the workpiece 
with the HEIDENHAIN KT Edge Finder or with a tool. Description of 
the probing functions: See "Probing Functions for Datum Setting" on 
page 28
Of course, you can also set datum points in the conventional manner 
by touching the edges of the workpiece one after the other with the 
tool and entering the tool positions as datum points (see examples 
following this page).
The datum table can hold up to 99 datum points. In most cases this 
will free you from having to calculate the axis travel when working 
with complicated workpiece drawings containing several datums.
Datum settings are performed in the ACTUAL VALUE operating mode 
and define the relationships between the axis positions and the 
display values. If necessary, the datum table’s values may be changed 
by entering a value directly.
See Job Setup for setting the datum value directly.
Datum selection (Mill only)
In ACTUAL VALUE mode, the Up/Down arrow keys may be used to 
select the next or previous datum number.
Tool selection (Turn only)
In ACTUAL VALUE mode, the Up/Down arrow keys may be used to 
select the next or previous tool number.