HEIDENHAIN CNC Pilot 4290 V7.1 - Manual (Page 39)

HEIDENHAIN CNC PILOT 4290 39
1
.4 F
undamentals
1.4 Fundamentals
Position encoders and reference marks
The machine axes are equipped with position encoders that register
the positions of the slide or tool. When a machine axis moves, the
corresponding position encoder generates an electrical signal. The
control evaluates this signal and calculates the precise actual position
of the machine axis.
If there is a power interruption, the calculated position will no longer
correspond to the actual position of the machine slide. To recover this
association, incremental position encoders are provided with
reference marks. The scales of the position encoders contain one or
more reference marks that transmit a signal to the control when they
are crossed over. From the signal the CNC PILOT can re-establish the
assignment of displayed positions to machine positions. For linear
encoders with distance-coded reference marks the machine axes
need to move by no more than 20 mm, for angle encoders by no more
than 20°.
With absolute encoders, an absolute position value is transmitted to
the control immediately upon switch-on. In this way the assignment
of the actual position to the machine slide position is re-established
directly after switch-on.
X (Z,Y)
X
MP
Zref
Xref
M