Alarms provide on/off control, warn of trouble, or provide emergency shutdown by sending one or more alarm (relay) outputs when a monitored process signal falls outside of a selected high and/or low limit.  Alarms are also known as Switches, Trips, On/Off Controllers, Annunciators, Comparitor, Logic Solver, Shutdown Alarm, Rate-of-Change Alarm, Differential Alarm, Safety Interlock, Sensor Failure Monitor, Trip Amplifier, Current Switch, Hard-Wired Alarm, and many others.