The alarm card has three primary functions. It provides a visual display of three severity levels of alarms (critical, major, and minor) detected by the system through the maintenance bus. The three pairs of alarm LEDs (critical and major alarm LEDs are red, minor alarm LEDs are amber) can warn of an over-temperature condition on a component in the card cage assembly, a fan failure in a blower module, an over-current condition in a power supply, or an out-of-tolerance voltage on one of the cards in the upper or lower card cage.The threshold levels for triggering the different stages of alarms are set by software. The RP continuously polls the system for temperature, voltage, current, and fan speed values. If a threshold value is detected, the RP sets the appropriate severity level of alarm on the alarm card lighting one of three pairs of LEDs and energizing the appropriate alarm card relays activating any external audible or visual alarms.It provides a connection point for the system to connect to two site-wide external alarm systems. Two redundant, 25-pin D-sub connectors (ALARM1 and ALARM2) on the alarm card faceplate are tied directly to the critical, major, and minor alarm relay normally open, normally closed, and common contacts. You can only attach safety extra-low voltage (SELV) external alarm circuits to the two alarm card connectors. The external alarm can be visual or audible. Audible external alarms can be reset by the cutoff switch on the alarm card faceplate. Visual alarms are reset by software.It also provides visual status of the clock and scheduler cards and the switch fabric cards. Five pairs of LEDs (one pair for each slot in the lower card cage) provide a visual status of the switch fabric.