Audio International, Inc. MSM2921-0x-x Installation
Document #540186, Rev. IR, 2/2000
Page 7 of 11
3.4
Wiring
Requirements
3.4.1 Introduction
The installing agency shall supply and fabricate all external cables
and mating connectors. The length and routing of external cables
must be carefully studied and planned before attempting installation
of the equipment. Allow adequate space for installation of cable
and connectors. Avoid sharp bends and placing cables near
aircraft control cables. Maintain a minimum clearance of three (3)
inches from any control cable. If wiring is run parallel to
combustible fluid or oxygen lines, maintain a separation of six (6)
inches between the lines.
3.4.2 Power
Wires
All power and ground wires shall be 22 AWG, minimum. Power
ground wires shall be grounded within twelve (12) inches of the
unit. All wires shall be in accordance with MIL-W-22759 or
equivalent. Twisted, shielded cable shall be in accordance with
MIL-W-27500 or equivalent. Protect power wires with circuit
breakers or fuses located close to the electrical power source bus.
3.4.3 AI’s Proprietary RS485 Serial Data Bus
The MSM2921-0x-x is designed to interface with other AI
equipment via AI’s proprietary RS485 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-W-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 shall be terminated per AI’s proprietary RS485 specification.
All modules on AI’s proprietary RS485 serial data bus shall be
connected in a “daisy-chain” configuration. AI’s proprietary RS485
serial data bus specification is available upon request.
