From RegConfig in Connect mode via cable or Web Connection mode it is possible to see all the available alarms by entering the Alarms page:
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Once the alarm has been resolved, the red light turns off without any further operations.
Attention
Errors from 16 to 23 (Circuit limit temperature) must be reset by switching the heat/cold enable off and on again or by switching off and on the power supply to the REG.
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For more info about bus error trouble shooting see BUS REG WIRING BEST PRACTICE.