Case A): Test With Constant Load; Case B): Test With A Defined Load Step; Acknowledging Faults - Siemens Simatic Manual

Fail-safe function blocks for storage and retrieval machines
Safety notes and instructions
Parameter "T_INTERVAL" defines in which cyclic intervals it is necessary to test
the measuring equipment. The value to be configured here depends on the spe-
cific application, and is also dependent on the risk assessment and the actual
hardware architecture of the safety function.
3.9.3.4.1

Case a): Test with constant load

23. If a 0 signal is available at input CAL_MODE, then within T_SETTLE, the load measured at
LOAD1 and LOAD2 must assume the calibration value that can be parameterized at
CAL_VALUE – taking into account the tolerance parameterized at MAXTOL_CAL.
24. If this is not the case, then ERROR changes to a 1 signal, and at DIAG bit 4 is set.
25. For the time parameterized at T_TEST, the load value measured at LOAD1 and LOAD2 must
not deviate from CAL_VALUE by more than MAXTOL_CAL.
26. If this is not the case, then ERROR changes to a 1 signal, and at DIAG bit 5 is set.
27. After T_TEST expires, and for a valid load value, BUSY is reset to 0 and output TEST_OK is
set to a 1 signal.
28. If T_TEST is parameterized <= T_SETTLE, then DIAG bit 5 and ERROR are set to 1.
3.9.3.4.2

Case b): Test with a defined load step

29. If a 1 signal is available at input CAL_MODE, then the load value must go through a load
range (stroke). In this case, the signal at LOAD1 and LOAD2 must assume the expected
range of CAL_VALUE within T_SETTLE.
30. If this is not the case, then ERROR changes to a 1 signal, and at DIAG bit 4 is set.
31. During T_TEST, the measured range (stroke) must not deviate by more than MAXTOL_CAL
from the expected range (stroke) that can be parameterized at CAL_VALUE.
32. If this is not the case, then ERROR changes to a 1 signal and at DIAG bit 5 is set to 1.
33. If, after T_SETTLE expires, the measured signal level at LOAD1 and LOAD2 is not higher
than the initial value (before the test stroke was started) by the value CAL_VALUE (taking into
account MAXTOL_CAL), then ERROR is also set to 1 and DIAG bit 4 is set.
34. After T_TEST expires and there is a valid value for the load step, BUSY is reset to 0 and out-
put TEST_OK is set to a 1 signal.
35. If T_TEST is parameterized <= T_SETTLE, then DIAG bit 6 and ERROR are set to 1.
36. A successful test is signaled at block output TEST_OK using a 1 signal. BUSY is reset to 0.
TEST_OK remains set to 1 until the next time that TEST_REQ changes to 1 or a new test is
started
Note
A measuring equipment test is requested at each CPU stop-start transition.
3.9.3.5

Acknowledging faults:

37. DIAG and ERROR are reset to 0 with a positive edge at ACK, assuming that no other fault is
active.
38. The block immediately indicates that it can be acknowledged with a 1 signal at its output
ACK_REQ.
39. ACK_REQ is reset to 0 after a positive edge at ACK.
S7-Distributed Safety/SIMATIC Safety - fail-safe function blocks for storage and retrieval machines
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