To supervise the wiring from the M1 Main Board or from the M1XIN 16-Zone Input Expander the 2.2K Î© End Of Line (EOL) Resistor must be at the sensor for proper supervision of the loop (or wiring). In the event something should happen to the wire and there is a short in the wire (nail, screw, staple, etc.) this will cause the zone to appear violated on the keypad. If the wire is cut or broken this will also cause the zone to appear as violated. For a sensor with normally open contacts (for example smoke detectors) the EOL Resistor will go across the contacts at the sensor. In the event the wire is cut or broken this will cause a Trouble condition to be displayed on the keypad and a short will cause an alarm. . . A Supervised Power Supply would provide an output when AC Power is lost to the power supply and a separate output when the power supply detects the battery is low. The ELK P212S is a Supervised Power Supply and when connected to the M1 the power supply is supervised over the M1’s Data Bus — no physical outputs required. When the P212S is in standalone mode it has a separate Relay Output when AC Failure is detected and a separate Relay Output when the Battery fails the battery test.