Testing An External Brake; Testing A Motor Holding Brake - Siemens Simatic Manual

Fail-safe function blocks for storage and retrieval machines
Safety notes and instructions
The parameterization of input V_MAX_RELEASE must be adapted to the permis-
sible safely reduced velocity according to the application-specific risk assess-
ment.
Safety notes and instructions
Parameter "T_INTERVAL" defines in which cyclic intervals it is necessary to test
the brakes. The value to be configured here depends on the specific application,
and is also dependent on the risk assessment and the actual hardware architec-
ture of the safety function.
Note
A brake test is requested at each CPU stop-start transition.
Note
Block F_SAFE_POS signals a 0 signal at POS_VALID via output ERROR = 1. All
additional blocks, i.e. also F_BRAKE_TEST, indicate this state using an error
code; to avoid a flood of messages, ERROR is not again set to a 1 signal, assum-
ing that the block is not performing a brake test at this instant in time. If a brake
test is active, and a 0 signal is available at input POS_VALID, then ERROR is
also set to 1.
3.8.2.4

Testing an external brake

If a 0 signal is available at SEQUENCE_BR_1/2.BIT4, then an external brake is tested according to
the following scheme:
20. If a 1 signal is available at SBT_CLOSE_BR, then depending on the status of
SBT_ACTIVE_BR, the block deactivates either OPEN_BR_1 or OPEN_BR_2; i.e. it closes the
brake presently being tested. Within the time parameterized at
T_CLOSE_BR_1/T_CLOSE_BR_2 a 1 signal must be present at the feedback signal channel
FDBACK_BR_1/ FDBACK_BR_2.
21. If this is not the case, then the test is canceled as described above. ERROR and DIAG bit 0/1
(depending on the brake presently being tested) change to 1.
22. After T_CLOSE_BR_1/T_CLOSE_BR_2 has expired, and with a 1 signal at FDBACK_BR_1/
FDBACK_BR_2, the closed brake is signaled to the drive using SBT_FDBACK_BR = 1; the
drive then executes its test profile.
23. During the test, it is monitored as to whether at input SAFE_POS the value changes by a max-
imum of POS_TOLERANCE. If the change is higher, then the test is canceled as described
above. ERROR and DIAG bit 3 change to a 1 signal.
24. Once the drive has exited the test, using a 0 signal at block input via SBT_CLOSE_BR, the
command to open the brake is output.
25. A 1 signal is then again available at output OPEN_BR_1/ OPEN_BR_2.
26. After the time parameterized at input T_OPEN_BR_1/ T_OPEN_BR_2 there must be 0 signal
at the feedback signal channel FDBACK_BR_1/ FDBACK_BR_2.
27. If this is not the case, then the test is canceled as described above. ERROR and DIAG bit 0/1
(depending on the brake presently being tested) change to 1.
28. After T_OPEN_BR_1/ T_OPEN_BR_2 has expired, and with a 0 signal at FDBACK_BR_1/
FDBACK_BR_2, the opened brake is signaled to the drive using SBT_FDBACK_BR = 0.
29. If the brake was successfully tested, then the drive signals this using SBT_FINISHED = 1.
30. For a successfully completed test, a 1 signal is available at input SBT_RESULT.
31. This test pattern is possibly repeated for the second brake, or, depending on
SEQUENCE_BR_2.BIT4, the following test pattern is used for the second brake:
3.8.2.5

Testing a motor holding brake

If a 1 signal is available at SEQUENCE_BR_1/2.BIT4, then a motor holding brake at the drive is tested
according to the following scheme:
32. In this mode, the drive directly controls the brake. This means that the drive autonomously ex-
ecutes its test profile; the block ignores SBT_CLOSE_BR.
S7-Distributed Safety/SIMATIC Safety - fail-safe function blocks for storage and retrieval machines
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