GAI-Tronics 12389-001 NOVA PA/GA Systems S.M.A.R.T. Modules - Manual (Page 6)

Pub. 42004-674L2H
NOVA P UBLIC A DDRESS S YSTEMS - S.M.A.R.T. M ODULES P AGE 4 of 24
f:\standard ioms - current release\42004 instr. manuals\42004-674l2h.doc
12/13
Locating NOVA S.M.A.R.T Modules in the Central Cabinet
The NOVA S.M.A.R.T. Modules must be housed in a cabinet or enclosure located in an environmentally-
controlled area. In larger installations, an auxiliary panel devoted to some of the modules is desirable.
The optimum configuration is to have the installed modules horizontally in “snap-track” style mountings
that directly face the technician. When mounted in this manner, all board-mounted controls and
connectors are easily accessible.
Central Processor Unit
The NOVA Central Processor Unit controls larger, more complex systems, and is usually housed in the
central cabinet along with other system equipment.
The CPU polls the various NOVA S.M.A.R.T Modules via a common RS-485 serial bus and sends
commands, as needed, to monitor the system health and supervise the ALC modules. The system CPU is
responsible for setting up both manual and automatically-initiated voice paging and the monitoring of
various alarm inputs.
Line Integrity Module (LIM)
Description
The GTC 12389-001 LIM Module consists of two PCBAs, the GTC 69389-01x LIM Speaker Line
Termination PCBA and the GTC 69389-02x LIM Controller PCBA, connected by a ribbon cable. The
LIM can monitor the speaker wire line integrity by measuring the resistance of up to eight zones or
speaker loops and reports faults on the line. When attached to a remote loudspeaker or ac power line, the
LIM breaks the dc loop continuity and isolates the gap with a large capacitance. The LIM monitors the dc
continuity of the loop by applying a selectable calibrated dc current across the isolating capacitors and
monitoring the dc portion of the loop for changes of more than 20% in loop resistance.
Furthermore, a test for leakage to earth is conducted by applying a dc voltage between the line loop and
earth ground and monitoring the current drain on the applied potential to determine acceptable limits of
leakage to earth. The application of excitation current and the measurement of the result are under the
control of a microcontroller and are multiplexed over eight lines per module.
In a complex alarm management system, the LIM communicates the alarm status with the system CPU
via RS-485. Under RS-485 (advanced) control the test interval is under the supervision of a system
central processor unit. This control can include modification and subsequent overwrite of an individual
line mean value in the form of positive or negative “tweaks.”
The LIM is also able to stand alone in a simple system and output alarm status on eight line-unique,
optically-isolated alarm closures. The supervised or stand-alone mode selection is via the address jumper
field, JU2 through JU5 on the LIM Controller PCBA.