Emergency alarm system activate button function - GF82.25-P-4100-04T

The emergency alarm system trigger button (S62/6)  is monitored by the multifunction control unit for special-purpose vehicles (MSS) (N26/9).  If the emergency alarm system activate button (S62/6) is pressed, the input of the special vehicle multifunction control module (MSS) (N26/9)  is short-circuited to ground to generate an emergency alarm.

For line monitoring  purposes the emergency alarm system activate button (S62/6) has a resistor (sensing resistor) connected in parallel. A small test current flows through this resistor when the emergency alarm system activate button (S62/6) is at rest. When the current drops below a defined threshold this indicates an open circuit.