US Patent 11774127 Building system controller with multiple equipment failsafe modes

An HVAC controller provides control values to or more output ports of the HVAC controller. Operation of the HVAC controller is monitored for one or more irregularities. When one or more irregularities in the operation are identified, a hold mode is entered. The hold mode includes holding the one or more current control values on the one or more output ports of the HVAC controller until the one or more irregularities in the operation of the HVAC controller are corrected or a predetermined hold time expires, whichever occurs first. When the one or more irregularities in the operation of the HVAC controller are not corrected before the predetermined hold time expires, a back off mode is entered. The back off mode includes setting each of one or more control values on one or more output ports of the HVAC controller to a corresponding configurable back off value.