XI. MPU Diagnostic LEDs

The MPU Diagnostic LEDs serve several functions. One function is the “lowest assignable address.” This is an aid in sequentially assigning the appropriate address on each keypad. When the system is turned on, and none of the keypads have been addressed,

Fig. 15: Diagnostic LEDs

DIAGNOSTIC CONTROL

REFER TO MANUAL

MUTE UNIT ON

the diagnostic LED 0 should flash every 0.8 seconds. This means the first DIP switch on the keypad should

0 1 2 3

N.O. G +12V G

-INPUT- -OUTPUT-

be set in the “down” position, and the other three should be in the “up” position. This sets that keypad for zone 1.You will then see diagnostic LED 1 begin to flash.

This is indicating the next available zone setting, which is the second DIP switch in the “down” position and the other three in the “up” position. The next available address would then be zone 3, which is the first two DIP switches in the “down” position and the third and fourth DIP switches in the “up” position, which is indicated by diagnostic LED 0 and LED 1 flashing simultaneously. As each keypad is set, the LEDs will continue to cycle to the next address, with the flashing LEDs indicating which of the four address DIP switches should be in the “down” position (Fig. 15).

Important Note: Once a keypad has been addressed, it should be left hooked up to the system. This will keep the diagnostic LEDs accurately displaying the next available address.

If the MPU’s bus transceiver is functioning properly, one or more of the Diagnostic LEDs will flash continually every 0.8 seconds. If the MPU’s bus transceiver sees a short-circuit on the bus, all four LEDs will flash ON twice every 0.8 seconds.

If the MPU is not processing normally due to a malfunction of the micro controller, all four LEDs will flash ON three times every 0.8 seconds.

A steadily flashing LED indicates a properly functioning MPU. If all four LEDs are flashing twice every 0 .8 seconds, there is a short-circuit that is most often a result of improperly wired Cat-5 cables. If all four LEDs flash three times every 0.8 seconds, there is a malfunction of the micro controller. If this should occur, please contact NUVO for proper warranty service.

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