Siemens SINUMERIK 840D sl Function Manual page 264

Connecting sensors and actuators
8.5 Safe programmable logic
● A reference checksum is calculated when booting and for changes/saving the file by the
NCK-SPL (/_N_CST_DIR/_N_SAFE_SPF) - it is entered into the program as a comment:
Example: ; SAFE_CHECKSUM = 000476bbH
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.
● The system variables $A_INSIP(D), $A_OUTSIP(D), $A_INSEP(D), $A_OUTSEP(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 8-3 Response to SPL errors
Event
Crosswise data comparison
NCK-PLC identifies an error
SPL program file is to be changed (writ‐
ten, deleted, re-named, edited)
Protective mechanisms
The protective mechanisms that prevent changes to the NCK-SPL file and the NCK-SPL
instructions (statements) are only effective if MD $MN_PREVENT_SYNACT_LOCK[0,1] is
not equal to 0.
The machine OEM must ensure that the protective mechanisms are activated no later than
after the completion of the acceptance test and the values, set in MD
$MN_PREVENT_SYNACT_LOCK[0,1] are documented in the acceptance report.
After commissioning has been completed, the access rights to the SAFE.SPF file must be
set to the correct access level for writing/reading/deleting access operations (manufacturer
or service).
As long as the protective mechanisms for the NCK-SPL have not been activated
(MN_PREVENT_SYNACT_LOCK[0.1] equal to 0), Alarm 27095 is displayed when the
crosswise data comparison between the NCK and the PLC starts. This alarm can be
acknowledged with the NCK key so that the SPL can be commissioned.
Note
The SPL program must be addressed using upper case letters. Alarm 27097 is output if this
is not observed.
264
MD11500 $MN_PREVENT_
SYNACT_LOCK[m,n] equal to 0
Alarm 27090 is triggered
No response
WARNING
MD11500 $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 initiated
Function Manual, 12/2017, 6FC5397-4BP40-6BA1
Safety Integrated