Festo CMMT-AS-C2-11A-P3, Manual, Page: 34 / 44

Safety reference data of the SBC safety function
Wiring Two brakes
1)
With SBA evalu-
ation
2)
One brake
3)
Without SBA evalu-
ation
Hardware fault toler-
ance in accordance
with EN 61508, HFT 1 0
Factor of failures as a
result of shared cause
for non-recognisable
dangerous errors
β
in
accordance with
EN 61508
[%] 5
Classification in
accordance with
EN 61508 Type A
1) Connection of one brake to BR+/BR− and a second brake to BR-EXT; 2-channel wiring and request over #SBC-A and #SBC-B.
2) Monitoring of the safety function over the SBA diagnostic output through the safety controller at least 1 x within 24 h.
3) Connection of a brake either to BR+/BR− or to BR-EXT; 1-channel request over the safety controller through #SBC-A and #SBC-B; both
inputs must be bridged externally.
Tab. 16 Safety reference data of the SBC safety function
Remarks
– Dependent on the desired safety classification, the evaluation of the SBA diagnostic output by the
safety relay unit is required or not mandatory.
– To achieve the safety category Cat. 3, PL d, SIL 2 (or also Cat. 2, PL c/d) in connection with 2
brakes, the evaluation of the SBA diagnostic output is required.
– If an SBC function with more than Cat. 1, PL c is required, the diagnostic outputs must be checked
regularly, at least 1 x within 24 h, by the safety relay unit (
è EN ISO 13849-1, appendix G.2).
– The safety relay unit must request the safety function at least once within 24 h and thereby monit-
or the SBA diagnostic output to achieve a diagnostic coverage of at least 60 %. If the signal beha-
viour does not correspond to expectations, the system must be transferred into a safe condition
within the reaction time. Time monitoring must be planned in the safety controller.
The technical data for the SS1 safety function must be calculated individually according to the applica-
tion. Use the specified safety reference data for STO and SBC for the calculation.
Technical data
34 Festo — CMMT-AS-...-S1 — 2018-02