2
2-3
FM 351 Positioning Function Module
EWA 4NEB 720 6001-02
2.1 Ranges and Switching Points in the Region of the Target Position
This chapter gives information about the combined effects of individual ma-
chine data. You will find a description of the machine data in Chapter 8.
Each target position is characterized by a number of ranges which you para-
meterize by entering values. Each range carries out a different task:
Range Explanation
Switchover
difference
A specified displacement, defining the distance to the target, at which the drive switches from
rapid speed to creep speed.
Switch-off difference A specified displacement, defining the distance to the target, at which the drive is switched
off.
Standstill range A symmetrical range about the target position. This range becomes active when PEH is sig-
naled. If the range is left without a valid request, the FM 351 signals an error.
Target range A symmetrical range about the target position. The target is reached when the drive undercuts
the standstill velocity within this range.
The figure shows you how the switching points and ranges about the target
position are arranged.
Target
–1000 mm 1000 mm0
Switching point at the limit of the switchover difference, positive/negative
Switch-off point at the limit of the switch-off difference, positive/negative
1
2
3
4 5
6
Operating range
Target rangeStandstill range
1
2 3
4 5
6 7
7
Figure 2-2 Ranges and Switching Points Around the Target
Note the following rules for the ranges shown:
The half target range must be smaller than the switch-off difference (incl.
the limits).
The switch-off difference must lie within the relevant switchover differ-
ence.
The dynamic characteristics of the drive must be considered when input-
ting values so that a reliable approach to the target is possible.
Introduction
Definition of the
Switching Points
and Ranges
Position of the
Switching and
Monitoring Ranges
Rules for the
Ranges
Principles of Positioning
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