Audio International PA-7500A Installation Manual - page 8
Audio International, Inc. PA-7500A Installation
Document # 540056A, Rev. A, 7/2000
Page 7 of 11
3.4.4 AI Proprietary RS-485 Data Bus
The PA-7500A is designed to interface with other AI equipment via
AI’s proprietary RS-485 serial data bus. This is a bi-directional data
bus that allows multiple units to be connected simultaneously.
The data bus is to be implemented using a twisted shielded pair
cable in accordance with MIL-DTL-27500 or equivalent. The wire
size for the conductors in this cable is to be 22 AWG
,
MINIMUM.
The shield is to be connected wherever a shield pin is provided.
Shield terminations are to be made as close to the connector pin as
possible. In the event shield pins are not provided, the data bus
shield must be terminated per AI’s proprietary RS-485 specification.
All modules on AI’s proprietary RS-485 data bus shall be connected
in a “daisy-chain” configuration. AI’s proprietary RS-485 serial data
bus specification is available upon request.
3.5
Physical Characteristics
3.5.1 Refer to Section 5.0 for unit dimensions.
3.5.2 Refer to Section 6.0 for attachment points.
3.5.3 When mounting the unit, allow sufficient space for mating
connectors.
3.6 Electrical Characteristics
3.6.1 Refer to Section 5.0 for electrical specifications.
3.6.2 P1 is a 25-pin connector. The signals interfaced through P1 are left
/ right speaker, +28 VDC emergency power and woofer outputs.
Power requirement is +28 VDC at continuous power output at 12
amps (15 amp breaker – 4 channel). Emergency power input is
provided for cabin page and chime functions in case of power
failure.
3.6.3 P2 is a 37-pin connector. The signals interfaced through P2 are PA
/ chime, briefer, stereo left and right (high and low), data bus
control, and +28 VDC power. When the briefer key input is
activated, all entertainment audio will be muted. The PA key input
has the highest priority and will override all briefer and
entertainment audio inputs. When the PA source is keyed, all other
audio will be muted. Chime inputs will operate simultaneously with
the briefer.
.