Patent ID: 8508236

Claim:
An electronic device comprising: a circuit board having a set of input contacts, a set of output contacts and an electrical circuit connected between the input contacts and the output contacts, and a controller, wherein the controller is configured, at least once during operation of the device, to apply a predetermined test signal to the set of input contacts, to tap off a response signal at the set of output contacts, to carry out a signal analysis on the response signal, to compare a result of the signal analysis with an expected value stored in a memory of the controller, and if no match is determined between the signal analysis result and the expected value, to prevent, at least partially, further operation of at least part of the device, wherein the electrical circuit is configured as a passive network having a characteristic transfer function and comprises at least two separate partial circuits which, in the installed condition, are connected to electrically conduct by interaction with at least one of: at least one device component and at least one installation component, and wherein the test signal is at least one of a pulsed signal, an alternating current signal with a predetermined frequency and an alternating current signal with a sequence of predetermined frequencies.