Siemens Sinumerik 840D sl Function Manual page 92

Basics on the safety functions integrated in the system/drive
5.4 Actual value conditioning
Warning
!
The specific residual risks for 1--encoder systems (refer to Chapter 3.5 "Safety
information & instructions and residual risks) must be carefully taken into
consideration.
2- -encoder system
In this case, the safety--related actual values for an axis are supplied from 2 sepa-
rate encoders. In standard applications, the drive evaluates the motor encoder
(IMS) and the NC, the measuring system (DMS). The actual values are generated
in a safety--related fashion either directly in the encoder or in the Sensor Module
and are provided -- with no--reaction -- to the NCK and the drive using safety--rela-
ted communications via DRIVE--CLiQ. A separate connection or a separate Sensor
Module is required for every measuring system.
For a 2--encoder system, an encoder fault can result in a STOP F followed by
STOP B and STOP A -- as well as an immediate STOP A response.
Sensor Module cabinet mounted
(not used for encoders with
DRIVE- -CLiQ interface)
Figure 5-2 2--encoder system for a feed drive (FD), connected through 2 Sensor Modules
5-92
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) - - 10.2015 Edition
DRIVE- -
CLiQ
Machine table
Encoder
Gearbox
Motor (FD)
Linear scale
Back- -
lash
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