Festo CMTT-AS S1 Series, Description, Page: 14 / 46

Test pulses that occur simultaneously at SBC-A and SBC-B are not filtered. For this reason, the SBA
diagnostic output delivers a high level signal for the duration of these low test pulses.
Testing the safety sub-function SBC
Test inputs #SBC-A and #SBC-B separately from each other and together. The diagnostic feedback
may only be set to high level when inputs #SBC-A and #SBC-B are both requested. If the signal beha-
viour does not correspond to expectations, the system must be put into a safe condition within the
reaction time. It is essential that time monitoring be provided in the safety relay unit.
The safety sub-function SBC with feedback via SBA must be tested at least 1x within the space of 24 h.
•
Test SBA feedback based on the SBC-A and SBC-B level according to the following table.
#SBC-A (BR+) #SBC-B (BR-Ext) SBA
Low level Low level High level
Low level High level Low level
High level Low level Low level
High level High level Low level
Tab. 4 Testing all SBC levels
While you are testing the safety sub-function SBC, discrepancy error detection may be activated in the
CMMT-AS if the test lasts longer than 200 ms. If a corresponding error message is output by the basic
unit, you will need to acknowledge it.
Evaluation of SBA
Recommendation: Evaluation with every actuation.
•
Check SBA feedback whenever there is a request.
#SBC-A (BR+) #SBC-B (BR-Ext) SBA
Low level Low level High level
High level High level Low level
Tab. 5 Evaluation of SBC level
Product overview
14 Festo — CMMT-AS-...-S1 — 2018-10a