Self-test system

A self-test method for an electronic system comprising a plurality of fault-monitoring systems each of which is adapted to output a fault signal when an input indicates that the electronic system is in a fault condition associated with the fault-monitoring system, the fault-monitoring systems being arranged in a cascade fashion such that a fault signal output from one fault-monitoring system is provided as an input to a subsequent fault-monitoring system in the cascade of fault-monitoring systems, the method comprising:

• inputting the fault signal from one fault-monitoring system to a subsequent fault-monitoring system to simulate a fault condition associated with the subsequent fault-monitoring system.

An electronic system comprising at least one fault-monitoring system, the system. being arranged to:

• place the system into a first fault condition and monitor for the generation of a first fault signal from a first fault-monitoring device,
• on generation of a first fault signal from the first fault-monitoring device after placing the system into a first fault condition, store a record to this effect in non-volatile memory,
• on subsequent reversion of the system to a to a non-fault condition, check whether the non-volatile memory includes a record of a first fault signal and when the non-volatile memory does not include a record of such a first fault signal on subsequent reversion, generate an alarm signal.

A self-test method for an electronic system, the method comprising:

• placing the system into a first fault condition and monitoring for the generation of a first fault signal from a fault-monitoring device,
• on generation of a. first fault signal from the fault-monitoring device after placing the system into a first fault condition, storing a record to this effect in non-volatile memory;.
• on subsequent reversion of the system to a non-fault condition, checking whether the non-volatile memory' includes a record of a :first fault signal and when the non-volatile memory does not include a record of such a first fault signal on subsequent commencement, generating an alarm signal.