Siemens SIMATIC S5 Manual page 105

IP 266
Example C: The drive is behind the reference point switch.
N H
A A
V
for
V
rev
Encoder's zero mark
Figure 5-16. Reference Point Approach in Example C
Start the reference point approach with "Start". The drive then executes the
following movements:
1. First, the IP 266 accelerates the axis in a forward direction at the specified
acceleration rate. The drive is thus accelerated toward the hardware end limit
switch.
2. When it has reached reference speed 1, the drive moves at constant speed.
3. When the limit switch is reached, the IP 266 decelerates the drive at the
specified deceleration rate.
4. When the drive reaches zero speed, the IP 266 switches it into reverse, again
accelerating it until it reaches reference speed 1.
5. When the edge of the signal from the reference point switch goes from 0 to 1,
the IP 266 decelerates the drive to reference speed 2.
6. An edge change from 1 to 0 in the signal from the reference point switch sets
an internal Enable signal. When this signal is set (the drive is moving at
reference speed 2), the IP 266 waits for the next zero mark pulse from the
encoder. A change from 0 to 1 in the zero mark signal 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.
EWA 4NEB 812 6057-02
Machine Data, Modes and Traversing Programs
B A
REF
R
V 2
R: Reference point
Forward
H N
E E
V 1
s
V 1
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