The Cardinal range of intelligent iMDUs features an intuitive web based user interface, SNMP MIB based control and monitoring, e-mail messaging and alerts. The units have an error log to record events, power and current monitoring and an optional temperature and humidity sensor to monitor local conditions in the equipment rack. Single input and dual input versions are available. The dual input version enables main and back up power sources to be connectedto a single Cardinal unit. Switching to the back up input supply is automatic on power fail of the main source. The changeover system is designed to allow non phase coherent inputs to be switched.