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

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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:
MD36950 $MA_SAFE_MODE_SWITCH_TIME
for SINAMICS S120:
p9550 SI Motion SGE changeover tolerance time (Control Unit)
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 (peri-
pherals) and the sensors and actuators connected to them must always be subject
to a forced--checking procedure (see Chapter 5.3 "Forced checking procedure").
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.
SPL signals
The forced checking procedure of SPL signals is a part of the SPL functionality
(see Chapter 7.5 "Safe programmable logic (SPL))".
Once the external safety circuit has been wired, a two--channel SPL has been
created and the relevant safety functions configured and checked with an accep-
tance test, the long--term reliability of this function, verified using an acceptance
test, can be ensured:
© Siemens AG 2015 All Rights Reserved
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) - - 10.2015 Edition
Connecting Sensors/Actuators
7.1 Safety- -relevant input/output signals
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