Siemens SIMATIC FM 453, Руководство пользователя

Страница: 268 / 380

9-68
FM 453 Servo Drive / Step Drive Positioning Module
C79000-G7076-C453-01
9.6.4 Synchronization
When using incremental encoders, or stepper motors without encoders, at
switch-on there is an offset, which cannot be determined in advance, between
the internal position value in
the FM and the mechanical position of the axis. To establish the position ref-
erence, the value internal to the FM must be synchronized with the real posi-
tion value of the axis. Synchronization is performed by taking over a position
value at a known point of the axis.
When using absolute encoders (SSI), at switch-on there is already a defined
relationship between the position value internal to the FM and the mechani-
cal position of the axis. This reference can be adjusted by setting an absolute
encoder alignment value (see Section 9.3.9, Setting the reference point).
is the compensation value for numerical alignment of the internal FM posi-
tion value.
This signals the synchronization point of the axis, in some cases, with refer-
ence to the reference point switch (see Figure 5-5 “Zero reference mark
selection”).
is an operating mode used to position the axis at the reference point.
is a fixed point on the axis. It is:
S
The target coordinate in the Reference-Point Approach mode
S
Removed from the synchronization point by the amount of the reference-
point shift, in axes with incremental encoders or stepper motors without
encoders.
Difference in distance between the synchronization point and the reference
point.
The reference-point shift serves:
S
for numerical measuring-system readjustment when an encoder is
changed
S
as a displacement reserve to brake the drive if the synchronization point is
overshot.
The reference point switch selects the synchronizing zero marker on the tra-
versing path of the axis.
S
It is also the signal encoder for a speed reduction before the synchroniza-
tion point is reached.
S
It is connected to a digital input of the FM 453.
Overview
Absolute Encoder
Alignment
Zero Reference
Mark
Reference Point
Approach
Reference Point
Reference Point
Offset
Reference Point
Switch (RPS)
Description of Functions