9 Axis/PLC Interface (DB 32)
01.93
9.3 Signals to axis
b) Reference point approach with automatic direction recognition
Signal chart
8
6
3
V
Z
1
2
4
5
7
1:
Reference point approach speed
2:
Cutoff speed
3:
Starting point for reference point approach
4:
Measuring system zero mark signal
5:
*DECELERATION signal
6:
Actuating cam
7:
Limit switch
8:
Machine end, traverse path limit
Sequence 1:
The Z axis must be located at the starting point, e.g. in the negative direction from the referen-
ce point. The operator presses the Z + key declared as the starting key for reference point
approach. The axis approaches the machine end at which the reference point is located; the
direction is recognized by *DECELERATION signal = 1. As soon as the actuating cam passes
the limit switch, the *DECELERATION signal changes from 1 to 0; the axis decelerates to zero
and then accelerates to the cutoff speed in the opposite direction. When the actuating cam
has cleared the limit switch, the *DECELERATION signal changes from 0 to 1 and initiates the
approach to the next zero mark of the measuring system. As soon as the zero mark signal is
given, the axis homes in to the reference point.
Sequence 2:
If the axis is already located between the machine end and the reference point at the start of
the reference point approach (*DECELERATION signal = 0) and the Z + key is then pressed,
the Z axis approaches the reference point in the negative direction at the cutoff speed.
Note:
The reference point approach of the C-axis is described in the Function Manual "Extended
Spindle Functions".
9
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12
©
Siemens AG 1991 All Rights Reserved 6ZB5 410-0HE02
SINUMERIK 880 (PJ)
