US Patent 7688230 Switching device with critical switch detection

A system is provided comprising a switching device and a response module. The switching device has a critical switch and a plurality of non-critical switches. The switching device generates an analog output voltage based on a switching state of the critical switch and each of the non-critical switches. The response module monitors the analog output voltage. The response module detects when the critical switch is closed, regardless of whether any non-critical switch is closed or any non-critical switch is open.