Abstract: A control circuit includes a latching relay, a power loss activation circuit, and a watchdog circuit. A microcontrol unit (MCU) communicates with the watchdog circuit in a normal operation of the control circuit. As an action of a failsafe precaution in the event of a main power loss or a component failure, the MCU stops communicating with the watchdog circuit, at which point the watchdog circuit instructs the power loss activation circuit to continue operation of the control circuit. The control circuit further operates to implement mitigation operations in the event of a main power loss or component failure.

Abstract: A fault tolerant interface includes a sensor and a safety control that are electrically connected to each other by a single wire. The sensor is configured to provide various signals to the safety control dependent on environmental parameters. Based on the ignal received by the safety control, the fault tolerant interface may act accordingly and place the overall system in a mitigative state in the event of a fault state or an alarm state. Data and fault or alarm states are detected by determining a first time interval between a first edge and a second edge of a signal, wherein an edge is one of a transition of the signal from a first voltage to a second voltage or a transition of the signal from the second voltage to the first voltage on a single wire. Data values versus fault or alarm states are assigned based on whether a current time interval corresponds to the first time interval or the second time interval, or another time interval associated with alarm or fault states.