Crosswise Data Comparison - Siemens SINUMERIK 840D sl Function Manual

Basics on the Safety Functions Integrated in the System/Drive

5.2 Crosswise data comparison

Warning
!
The monitoring clock cycle determines the response time of the safety-related
functions. It must therefore be selected to be <= 25 ms. The higher the monitoring
cycle setting, the greater the amount by which the monitored limit value is violated
in the event of an error and the more that the drive(s) overshoots.
5.2 Crosswise data comparison
The continuous comparison of the safety-relevant data in the monitoring channels
carried-out in the SI monitoring clock cycle is known as "crosswise data compari-
son" (CDC).
The following apply to the axial 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 initi-
ating a response (e.g. tolerance for crosswise data comparison of actual positions).
A distinction is made between:
S Crosswise data comparison between the NCK and drive
S SPL crosswise data comparison between the NCK and PLC (see Section 7.3
"Safe programmable logic (SPL)".
Error response
If the crosswise data comparison identifies an error, then this results in a stop re-
sponse (see Section 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 axial MD 36992 is used: $MA_SAFE_CROSSCHECK_CYCLE and the
general MD 10092: $MN_INFO_CROSSCHECK_CYCLE_TIME. If the monitoring
clock cycle is modified, then the crosswise comparison clock cycle is also
changed.
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SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 03.2006 Edition
© Siemens AG, 2006. All rights reserved
03.06