HEIDENHAIN TNC 335 Technical Manual - Manual (Page 291)

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TNC 360 14 Datum Correction 8/95
14 Datum Correction
The PLC datum correction function is used to shift the zero or datum point with the PLC program.
Datum corrections are required for machines that have swivel heads, e.g. when swivelling the head
causes a correction in the X/Z axis.
Each axis (X, Y, Z, 4) is assigned a doubleword (D528 to D540) for the correction value. If a value for
the appropriate axis is entered via the PLC program and strobe marker M2716 is set, then a datum
correction will be active at the next M/S/T strobe. The correction is computed in the actual position
display. The display then indicates the shifted system of coordinates.
Example:
Actual position display for X axis without correction = 50
Correction in D528 = +20
Strobe marker M2716 set, i.e. correction is active
New actual position display X= +70
The corrections can be transferred to doublewords, D528 to D540, from different memory areas:
- Enter values in MP4210.0 to MP4210.47 and they will also be in D768 to D956; now copy values
via PLC program into D528 to D540.
If several datum shifts are executed in one axis, the correction values refer to the uncorrected
reference system. In datum compensation with the value 0, previous (axis specific) corrections are
canceled.
D528 Datum correction for X axis
D532 Datum correction for Y axis
D536 Datum correction for Z axis
D540 Datum correction for 4th axis
M2716 Strobe marker for datum correction