HEIDENHAIN TNC 407 (280 580) User Manual - Manual (Page 164)

5-65 TNC 425/TNC 415 B/TNC 407
5 Programming Tool Movements
Fig. 5.57: Scale reference point and machine zero on
scales with one or several reference marks
5.7 M Functions for Contouring Behavior
X(Z,Y)
X
MP
X(Z,Y)
X
MP
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 are used to indicate 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 indicated by the left-
most reference mark (at the beginning of the measuring range).
Machine zero – miscellaneous function M91
The machine zero point is required for the following
tasks:
• Defining the limits of traverse (software limit
switches)
• Moving to machine-referenced positions (e.g.
tool-change position)
• Setting the workpiece datum
In the machine parameters the machine tool builder
defines the distance for each axis from the scale
reference point to the machine zero point.
If you want the coordinates in a positioning block to
be referenced to the machine zero point, end the
block with the miscellaneous function M91.
Coordinates that are referenced to the machine
zero point are indicated in the display with REF.
Machine datum – miscellaneous function M92
In addition to the machine zero point, the machine
tool builder can define another machine-referenced
position, the machine datum.
The machine tool builder defines the distance for
each axis from the machine zero to the machine
datum.
If you want the coordinates in a positioning block to
be referenced to the machine datum, end the block
with the miscellaneous function M92.
Radius compensation remains active in blocks that are programmed with M91 or M92. The tool length is not com-
pensated.