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Werk #22111: Rittal CMC III: discover phase services when the sensor description is used

Component Checks & agents
Title Rittal CMC III: discover phase services when the sensor description is used
Date Sep 11, 2026
Level Trivial Change
Class Bug Fix
Compatibility Compatible - no manual interaction needed
Checkmk versions & editions
3.0.0b1
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT
2.5.0p14
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT
2.4.0p37
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT

Previously, if the discovery ruleset Rittal CMC III discovery was set to Use sensor description, the phase services of a CMC III PDU were not discovered at all. The Check_MK Discovery service reported check failed - please submit a crash report! with KeyError: 'DescName', and on the Service discovery page the already monitored phase services showed up as vanished without anything replacing them. This has been fixed.

A word on the resulting service names, because they may look odd at first: unlike the other CMC III sensors, a phase has no description of its own. The device describes each of its measurements separately, for example "L1 Voltage", "L1 Current" and "L1 Power". A phase service is therefore named after the first of those measurements, so you will see a service like Input 1-3 L1 Voltage that reports the voltage, current, power and energy of phase L1. If you prefer different names, the ruleset Translation of service descriptions can be used to adjust them.

Sensors that report no description at all now keep the device and sensor name as their item, for example Temperature Ambient HUM_RA-01-E. Some CMC III sensor modules omit the description of their temperature channel, and those sensors previously caused the same crash.

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