Siemens SIMATIC FM 453, Manual

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9-19
FM 453 Servo Drive / Step Drive Positioning Module
C79000-G7076-C453-01
When crossing the RPS, a signal length of
∆
t
w
2
@
FM cycle must be as-
sured!
The following table shows you the exact location of the synchronization
point on the current-sourcing pattern zero or zero pulse external.
Synchronization Point
Encoder Selection in MD37
Applicable for Type (0 – 3) of the Reference
Point Approach per MD18
Current-sourcing pattern zero
RPS
V
R
Zero pulse external (NIX)
RPS
V
R
NIX
Center
If it is possible for the axis to be “behind” the reference point switch when
you start reference point approach, a reversing switch can be installed at the
end of the axis in the approach direction, in order to reverse the axis in the
direction of the reference point switch.
On axis movements with referencing feed, a signal length of
∆
t
w
2
@
FM
cycle must be assured for the reversing switch!
Example
Approach direction from
MD18
Reversing
switch Emer-
gency limit
switch
Reference point
Axis position
RPS
The value for the reference-point shift (MD27) is traveled after the synchro-
nization point is reached.
The following table describes how a reference can be recorded without a ref-
erence-point switch.
Recording of syn-
chronization
Sequence of movements
R+, R–
or Start 1. Instantaneous position is defined as reference point (refer-
ence-point coordinate).
2. Value for reference-point shift is traveled.
Using a Reversing
Switch
Without
Reference-Point
Switch (RPS)
Description of Functions