Manual – MOVIDRIVE® MDX61B Safety Module Option MOVISAFE® DCS..B
81
6
Configuring the measuring sections
Startup
• Absolute value source
The "Source absolute" selection field is used to define the source for the absolute
value of "encoder 2". "External encoder" means an SSI absolute encoder connected
to terminal X85. "Backplane bus abs." means the absolute value of MOVIDRIVE
®
B
via backplane bus.
– "External encoder" setting:
If an SSI absolute encoder is operated directly on the DCS..B option or via an
encoder split cable, the physical resolution of the encoder also limits the
maximally possible travel distance of the application. When using an SSI absolute
encoder, this means that the DCS..B option can only evaluate its resolution
(24 bits) of "4096 increments/revolution × 4096 revolutions".
– "Backplane bus abs" setting:
If the absolute encoder is connected to MOVIDRIVE
®
B, for example for position-
ing, then the internal value of the encoder can be used for position processing.
The advantage is that MOVIDRIVE
®
B can process the physical overflow of the
encoder (> 24 bits). In this way, the position range of the DCS..B option is
expanded from 24 bits to 31 bits with the same encoder.
Example:
For crane travel, the gear ratio i = 11 and the circumference of the drive wheel
(250 mm) results in a resolution of 180224 increments/m.
The maximum travel distance in the "External encoder" setting is determined
as follows:
Maximum positioning range of the DCS..B option: 2
24
− 1 = 16777215 increments
The maximum travel distance in the "Backplane bus abs." setting is determined
as follows:
4030466315
4030470155
Increments
m
m
Drive wheel circumf.
Encoder resolution
Revolutions
=×
1
1180224
1
025
11 4096
Increments
m
m
m
Increments
m
=××
.
Maximum travel distance
Max. positioning range
Increments
=
mm
m
increments
increments
m
93 09
16777215
180224
. =
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