Rittal CMC III Processing Unit Frequently Asked Questions

FAQ – CMC III
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If the CMC III I/O Unit is to be connected with several fault-message contacts of a
device, how must it be wired?
The digital inputs of the CMC III I/O Unit are connected internally to a shared GND. This
makes it important that the pin assignment of the digital inputs is observed when it is
connected with several fault-message contacts of a single device. The shared GND for the
digital inputs is always on the right-hand pin.
How, for example, is a lamp connected to the relay output?
The relay outputs on the CMC III I/O Unit as well as the relay output on the rear of the
CMC III Processing Unit are pure switching contacts and do not provide any 24 V power
supply. This must come from an external power supply for the connection of a lamp. The
relay has the connections: Common (C), Normally Open (NO) and Normally Closed (NC).
The connection must be made as for a normal relay using the NO or NC and C contacts.

Rittal CMC III Processing Unit Specifications

General

Brand	Rittal
Model	CMC III Processing Unit
Category	Control Unit
Language	English