Test Sequence And Error Handling - Siemens Simatic Manual

Fail-safe function blocks for storage and retrieval machines
3.8.2.3

Test sequence and error handling

1. After the time parameterized at T_INTERVAL has elapsed, the block requests a brake test via
output TEST_REQ.
This is started using a rising edge at EXECUTE, BUSY is set to 1.
2. The test sequence for the particular brake is parameterized using input SEQUENCE_BR_1 or
SEQUENCE_BR_2.
Specifying SEQUENCE_BR_1/2 bit-coded:
bit 0: Test with test sequence 1 positive
bit 1: Test with test sequence 1 negative
bit 2: Test with test sequence 2 positive
bit 3: Test with test sequence 2 negative
bit 4: 0: external brake; 1: Motor holding brake
Brake 1 is always tested first, followed by brake 2.
3. When the first error occurs, the test is canceled. ERROR then changes to 1, BUSY is reset to
0.
4. At BR_1_OK or BR_2_OK a 0 signals that the test for this brake was not successful, output
TEST_OK is set to zero.
5. These signals are only set back to 1 after the test has been successfully completed.
6. As long as the test was not successfully completed, at SLS_THRESHOLD, the velocity pa-
rameterized at input VMAX_RELEASE is output, and output TEST_OK has a 0 signal.
7. RELEASE_DIR is set to 0 if the test was successful. By appropriately controlling the drive-side
SDI safety function, it is possible to permit further travel only in the safety-related direction;
i.e., for a hoisting gear, slowly downwards. As soon as the test was successfully completed,
RELEASE_DIR again outputs a 1 signal.
8. If SAFE_V exceeds the value of SLS_THRESHOLD, then SLS_OK changes to 0, and DIAG
bit 2 is set.
9. If both brakes were successfully tested, then at SLS_THRESHOLD the maximum value (max-
imum INTEGER value = 32767) is output for the permissible velocity.
10. DIAG and ERROR are reset to 0 with a positive edge at ACK, assuming that no other fault is
active.
11. The block immediately indicates that it can be acknowledged with a 1 signal at its output
ACK_REQ. ACK_REQ is reset to 0 after a positive edge at ACK.
12. If a brake test was unsuccessful, then a new test can be started after first acknowledging us-
ing a positive signal edge at ACK. To start, a positive edge is required at EXECUTE.
13. If a 0 signal is available at V_VALID, then DIAG bit 15 is set.
14. Further, ERROR changes to 1 and SLS_OK to 0, if the block is presently in the retraction
mode.
15. To exit this state, V_VALID must be again set to a 1 signal using F_SAFE_POS by acknowl-
edging.
16. If the test is started using EXECUTE = 1, then the block initially signals this at output BUSY
using a 1 signal. This and all additional SBT_... output parameters of the block must be inter-
connected with the corresponding signals to control the drive-side SBT function.
17. Depending on the parameterized test sequence, in the block, outputs SBT_BR_SELECT,
SBT_TORQUE_DIR and SBT_SEQUENCE are switched.
18. If the test was started, then the drive must provide a feedback signal indicating this condition
at input SBT_SELECTED. The user must also appropriately establish this signal interconnec-
tion.
19. The drive provides a feedback signal about the brake that has just been tested at input
SBT_ACTIVE_BR. This feedback is used to check the plausibility. Block sets ERROR as well
as DIAG bit 6 if there is a contradiction to the control signals.
Warning
The interconnection of output RELEASE_DIR must match the selection of the SDI
drive function for the direction to be inhibited depending on the specific application.
For RELEASE_DIR = 0, motion in this direction should no longer be possible.
It is absolutely essential that the block output is interconnected with the correct sig-
nal for controlling the drive.
Otherwise, an impermissible motion toward the end stops is possible, which cannot
be identified internally by the block.
S7-Distributed Safety/SIMATIC Safety - fail-safe function blocks for storage and retrieval machines
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