Siemens SIMATIC S5 Manual page 104

Machine Data, Modes and Traversing Programs
Example B: The drive is positioned to the reference point switch
N H
A A
V
for
V
rev
Encoder's zero mark
Figure 5-15. Reference Point Approach in Example B
This represents a special feature of the "Approach reference point" mode.
Start the reference point approach with "Start". The drive then executes the
following movements:
1. The IP 266 accelerates the drive immediately in the specified direction until it
reaches reference speed 2.
2. A change from 1 to 0 in the signal from the reference point switch sets an
internal Enable signal. When this signal is set, the IP 266 waits for the next zero
mark pulse from the encoder. A change of the zero mark signal from 0 to 1 sets
the reference point. The reference point coordinate specified in the machine
data is assigned to this position. At the same time, the IP 266 decelerates the
drive to zero speed. The actual value is acquired and displayed. When the drive
is at zero speed, the actual value is lower (i. e. more negative) than the
reference point coordinate.
5-32
A
B
REF
R
V 2
R: Reference point
IP 266
Forward
H N
E E
S
EWA 4NEB 812 6057-02