Festo — CMMT-ST-C8-1C-...-S0 — 2021-04b
Installation
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With this type of wiring, the safe controller cannot perform diagnostics on whether a diagnostic
contact of a CMMT-ST is permanently conductive with a short circuit on the output. For this reason,
this type of wiring is not permitted for operation with EC motors and the required safety classification
in accordance with SIL 3, cat. 3, Ple.
Fig. 7: Connection example for cross-wiring several devices without checking individual diagnostic
contacts
Connection Example for Cross-Wiring Several Devices with Checking the Diagnostic Contact
If it is required for the overall assessment of the system that the safe controller can perform diagnos-
tics with diagnostic contacts, the diagnostic contacts may not be connected in series. In these cases,
the diagnostic contacts must be individually connected on separate inputs of the safe controller.
The inputs #STO-A and #STO-B can continue to be wired in parallel.
