HEIDENHAIN TNC 407 (280 580) ISO Programming - Manual (Page 172)

5 - 3 9 TNC 426/TNC 425/TNC 415 B/TNC 407
5 Programming Tool Movements
Programming machine-referenced coordinates: M91/M92
Standard setting
Coordinates are referenced to the workpiece datum (see page 1-13).
Scale reference point
The position feedback scales are provided with one or more reference
marks. Reference marks define the position of the scale reference point. If
the scale has only one reference mark, its position is the scale reference
point. If the scale has several – distance-coded – reference marks, then
the scale reference point is the position of the leftmost reference mark (at
the beginning of the measuring range).
Machine datum – miscellaneous function M91
The machine datum is required for the following
tasks:
• Defining the limits of traverse (software limit
switches)
• Moving to machine-referenced positions (such
as tool change positions)
• Setting the workpiece datum
The distance for each axis from the scale reference
point to the machine datum is defined by the
machine manufacturer in a machine parameter.
If you want the coordinates in a positioning block to
be referenced to the machine datum, end the block
with M91.
Coordinates that are referenced to the machine
datum are indicated in the display with REF.
Additional machine datum – miscellaneous function M92
In addition to the machine datum, the machine
manufacturer can also define an additional machine-
based position as a reference point.
For each axis, the machine manufacturer defines
the distance between the machine datum and this
additional machine datum.
If you want the coordinates in a positioning block to
be based on the additional machine datum, end the
block with M92.
Radius compensation remains the same in blocks that are programmed with M91 or M92.
Fig. 5.48: Scale reference point and machine datum on
scales with one or more reference marks.
5.6 M Functions for Contouring Behavior
X(Z,Y)
X
MP
X(Z,Y)
X
MP