Siemens SINUMERIK 840D sl Function Manual page 201

03.06
Protective mechanisms
S The synchronous action IDs used for the NCK-SPL are protected from being
influenced by the PLC or other programs using MD $MN_PREVENT_SYN-
ACT_LOCK. It is then no longer possible to change these synchronous actions
(CANCEL, LOCK have no effect) once _N_SAFE_SPF has been started.
S System variables $A_OUTSI, $A_OUTSID, $A_OUTSE, $A_OUTSED,
$A_MARKERSI, $A_TIMERSI and $A_CMDSI are protected from being written
to by programs other than the NCK-SPL (/_N_CST_DIR/_N_SAFE_SPF). If an
error occurs, Alarm 17070 "Channel %1 block %2 data item write-protected" is
output.
S A reference checksum is calculated when booting by the NCK-SPL
(/_N_CST_DIR/_N_SAFE_SPF) - it is entered into the program as a comment:
Example:
The checksum is then cyclically re-calculated and compared with the reference
checksum. If a deviation is detected, Alarm 27093 "Checksum error NCK-SPL,
%1, %2, %3" is output.
S The system variables $A_INSIP(D), $A_OUTSIP(D), $A_INSEP(D), $A_OUT-
SEP(D) and $A_MARKERSIP(D) are only accessible during the commissioning
phase.
If NCK-SPL execution is interrupted for any reason or the SI system variables are
changed by another program, then this is detected by the cyclic crosswise data
comparison with the PLC.
Table 7-4 Response to SPL errors
Event
Crosswise data comparison
NCK-PLC identifies an error
SPL program file is to be changed
(written, deleted, re-named, edited)
© Siemens AG, 2006. All rights reserved
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 03.2006 Edition
; SAFE_CHECKSUM = 000476bbH
MD 11500 $MN_PREVENT_
SYNACT_LOCK[m,n] equal to 0
Alarm 27090 is triggered
No response
Connecting Sensors/Actuators
7.3 Safe programmable logic (SPL)
MD 11500 $MN_PREVENT_
SYNACT_LOCK[m,n] not equal to 0
Alarm 27090 is triggered and in
addition, STOP D/E is triggered
Alarm 27093 is triggered
7-201