Crosswise Data Comparison (Cdc) - Siemens Sinumerik 840D sl Function Manual

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5.2

Crosswise data comparison (CDC)

The continuous comparison of the safety--related data in the monitoring channels
carried out in the SI monitoring clock cycle is known as "crosswise data compari-
son" (CDC).
The following apply for the axis--specific monitoring functions: In the case of "non--
steady--state" data, tolerance values defined using machine data are used by
which amount the results of the two channels may deviate from one another
without initiating a response (e.g. tolerance for crosswise data comparison of
actual positions).
A distinction is made between:
S Drive CDC between the drive and Motor Module (refer to Chapter 4 "Safety
functions integrated in the drive").
S Axis CDC between the NCK and drive (refer to Chapter 6 "Safety functions inte-
grated in the system/drive").
S Communication CDC between the NCK and PLC (refer to Chapter 7.2, "Con-
necting I/O via PROFIsafe" and Chapter 7.4 "Safety--relevant CPU--CPU com-
munication (F_DP communication)").
S SPL--CDC between the NCK and PLC (refer to Chapter 7.5, "Safe program-
mable logic (SPL)").
Error response
If the crosswise data comparison (CDC) identifies an error, then this results in a
stop response (refer to Chapter 6.3, "Safe Stops A--F").
In addition, safety alarms are output.
Note
If SGEs are quickly changed over several times this can initiate a STOP F.
Displays the crosswise data comparison clock cycle
To display the actual crosswise data comparison cycle time between the NCK and
drive, the axis--specific MD36992 $MA_SAFE_CROSSCHECK_CYCLE and gene-
ral MD10092 $MN_INFO_CROSSCHECK_CYCLE_TIME are used: If the monito-
ring clock cycle is modified, then the crosswise comparison clock cycle is also
changed.
The length of the crosswise comparison list depends on whether certain functions
have been enabled.
The CDC cycle active on an axis is displayed in the axis--specific MD36992
$MA_SAFE_CROSSCHECK_CYCLE.
The maximum CDC cycle time active on the axes is displayed in the NCK--specific
MD $MN_INFO_CROSSCHECK_CYCLE_TIME.
© Siemens AG 2015 All Rights Reserved
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) - - 10.2015 Edition
Basics on the safety functions integrated in the system/drive
5.2 Crosswise data comparison (CDC)
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