Ranges And Switching Points In The Region Of The Target Position; Ranges And Switching Points Around The Target - Siemens SIMATIC FM 351 Installation Manual

2.1

Ranges and Switching Points in the Region of the Target Position

Introduction
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.
Definition of the Each target position is characterized by a number of ranges which you para-
Switching Points
meterize by entering values. Each range carries out a different task:
and Ranges
Range
Switchover A specified displacement, defining the distance to the target, at which the drive switches from
difference 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.
Position of the The figure shows you how the switching points and ranges about the target
Switching and
position are arranged.
Monitoring Ranges
1
2
4
6
Figure 2-2 Ranges and Switching Points Around the Target
Rules for the Note the following rules for the ranges shown:
Ranges
FM 351 Positioning Function Module
EWA 4NEB 720 6001-02
Explanation
–1000 mm
4
2
Operating range
Switching point at the limit of the switchover difference, positive/negative
3
Switch-off point at the limit of the switch-off difference, positive/negative
5
Standstill range Target range
7
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.
Principles of Positioning
Target
0
6
7
5
3
1000 mm
1
2-3
2