Siemens Sinumerik 840D sl Function Manual page 89

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The forced checking procedure must be initiated by the user or integrated in the
process as an automatic procedure, e.g.:
S When the axes are stationary after the system has been powered--up
S When the protective door is opened
S In defined cycles (e.g. every 8 hours. The maximum permissible is once per
year).
S In the automatic mode, dependent on the time and event
The forced checking procedure also includes testing the safety--related sensors
and actuators at the safety--related inputs/outputs. In this case, the entire circuit
including the Safe Programmable Logic (SPL) is tested to ensure that it is correctly
functioning (refer to Chapter 7.1.2, "Forced checking procedure of SPL signals").
Warning
!
The test interval duration of max. 1 year may only be extended under the following
conditions:
S In the time after the test interval has expired, no hazards for personnel may be
allowed to occur -- they must be completely excluded (e.g. the protective door
is closed and is also interlocked)
S After the test interval has expired, before a possible hazard to personnel
(e.g. for a request to open a protective door), a test stop or a forced checking
procedure must be carried out to absolutely ensure the availability of the
shutdown paths and the safety--related inputs/outputs.
This means that for the duration of the automatic mode (with the protective door
closed and interlocked), a fixed cycle is not strictly specified. After expiry of the
time, the forced checking procedure can be carried out before the next opening of
the protective door.
Note
If the crosswise data comparison identifies an error, then this results in a stop
response (refer to Chapter 6.3, "Safe Stops A--F").
© Siemens AG 2015 All Rights Reserved
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) - - 10.2015 Edition
Basics on the safety functions integrated in the system/drive
5.3 Forced checking procedure
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