Siemens SINUMERIK 840D sl Function Manual page 226

Connecting Sensors/Actuators
7.3 Safe programmable logic (SPL)
Limitations
The user must take into consideration the following points regarding the functioning
of the crosswise data comparison:
S Both channels (NCK/PLC) must execute the same logic.
S Do not implement any response sequences or sequence controllers that are
externally controlled using short input pulses. This is because short pulses of
this type may only be sent and processed in one channel because of sampling
effects.
S Unused inputs/outputs/markers of the SPL must be assigned the default value
= 0; single–channel use of individual bits for non–safety relevant purposes is
not permissible.
S External STOPs must be enabled (they are also used internally) and can be
extracted from the SPL if required. The "external STOP A" must be parameter-
ized at the SPL interface for all safety axes using MD
$MA_SAFE_EXT_STOP_INPUT[0]. If this condition is not fulfilled, then Alarm
27033 is output.
S Crosswise data comparison checks whether the "commissioning phase" has
been completed. If errors are detected in the crosswise data comparison, a
"STOP D/E" is triggered on the NCK and drive depending on this criterion. If the
commissioning phase has not been completed after booting, Alarm 27095 "SPL
protection not activated" is repeatedly displayed (every 3 hours).
Motor
PROFIsafe
Process
Fig. 7-22 Communications between the NCK–drive–PLC components
7-226
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 05.2008 Edition
External
SGE/SGA
NCK signal processing
CDC
Bus
PLC signal processing
Internal
SGE/SGA
Interface
NCK– NCK
SPL SGE/SGA
signals
NCK monitoring channel
CDC
Drive monitoring channel
NC/PLC
interface:
PLC–
Axis/
SPL
spindle DB
Interface
System
© Siemens AG 2008 All Rights Reserved
05.08
Comparator
Data
CDC
Comparator
Data