5.9.9.2 SIL CL3 / PLe Dual Channel control
To achieve PLe / SIL CL3, the safe switching of the pulse inhibitor must be tested periodi
-
cally by analyzing the feedback signal from a safety control:
l
At the start of a system
l
At the restart after triggering a protective device
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At least every 8 hours by the operator.
The inputs STO1-ENABLE and STO2-ENABLE are switched in turns according to a defi-
ned test sequence. The switching state of the pulse inhibitor is available at a digital output
of the S700 and is analyzed by a safety control.
The test sequence for the functional test of the safe pulse inhibitor must be performed as
shown in the following time chart. Prerequisites for the start of the test sequence:
l
Operational readiness BTB/RTO = “1"
l
Enable signal ENABLE = “0"
l
STO1-ENABLE and STO2-ENABLE = “0"
Legend:
STO1-ENABLE: digital input, 1st switch-off path
STO2-ENABLE: digital input, 2nd switch-off path
STO-STATUS: digital output, switching state of pulse inhibitor
T1 … T5: Test sequence
Start: Start of test sequence
End: End of test sequence
50 S701x2-S724x2 Instructions Manual
Technical description 07/2014 Kollmorgen
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