Forced Checking Procedure Of Spl Signals - Siemens SINUMERIK 840D sl Function Manual

03.06
Different signal run times in the channels
The signal timing in the two monitoring channels varies (the PLC cycle time takes
up most of the available time in the drive monitoring channel). To prevent the
crosswise data comparison function from being immediately activated after a signal
change, a tolerance time is defined using the following machine data.
for 840D sl:
MD 36950: $MA_SAFE_MODE_SWITCH_TIME
for SINAMICS S120:
p9550: SI motion, SGE changeover, tolerance time
This data specifies the time period for which different signal states may be toler-
ated after the SGEs have been changed-over before an error message is output.
Note
System-related minimum tolerance time
2 x PLC cycle time (maximum cycle) + 1 x IPO cycle time
7.1.2

Forced checking procedure of SPL signals

Fundamentals
Safety-related input/output signals including the connecting cables to the I/O (pe-
ripherals) and the sensors and actuators connected to them must always be sub-
ject to a forced-checking procedure (see Section 5.3 "Forced checking proce-
dure").
The scope of the forced checking procedure should be implemented corresponding
to the subsequent conditions.
This means that the selection of a suitable forced checking procedure concept de-
pends on the specific application and the specific sensor and/or actuator; this deci-
sion must be made by the user. In this scope, the user must configure the forced
checking procedure.
© Siemens AG, 2006. All rights reserved
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 03.2006 Edition
Connecting Sensors/Actuators
7.1 Safety-relevant input/output signals
7-167