Audio international MSM2921-0x-x User manual

7300 Industry Drive, North Little Rock, AR 72117
Phone: [phone] Fax: [phone]
www.audiointl.com
Installation Manual
Model #: MSM2921-0x-x
Discrete to RS485 Converter Module
Document #540186

Audio International, Inc. MSM2921-0x-x Installation
Document #540186, Rev. IR, 2/2000 Page 2 of 11
Document Revision History
Rev. Level Date Description
IR 2/2000 Initial Release
Reference Documents
Document # Drawing # Description
N/A 522267 MSM2921-0x-x Outline Drawing
Service Bulletin List
Service
Bulletin # Subject Manual Revision Revision Date
Table of Illustrations
Illustration # Description Page #
1 Typical Application 5
2 Reference Drawings 10
PROPRIETARY INFORMATION NOTICE: Despite any other copyright notice, this document and
information disclosed herein contains confidential, proprietary designs owned by Audio
International, Inc. Neither this document nor the data contained herein shall be reproduced, used
or disclosed to anyone without the written authorization of Audio International, Inc.

Audio International, Inc. MSM2921-0x-x Installation
Document #540186, Rev. IR, 2/2000 Page 3 of 11
Table of Contents
Section Description Page
1.0 General Information ……………………………………………. 4
1.1 Introduction ……………………………………………………….. 4
1.2 Purpose of the Equipment ………………………………………. 4
1.3 Operational Features …………………………………………….. 4
1.4 Optional Equipment ……………………………………………… 4
2.0 Application ……………………………………………………….. 5
2.1 Introduction ……………………………………………………….. 5
2.2 Block Diagram –Typical Application …………………………… 5
3.0 Installation ……………………………………………………….. 5
3.1 Prior to Installation ……………………………………………….. 5
3.2 Unpacking and Inspection ………………………………………. 6
3.3 Cautions & Warnings …………………………………………….. 6
3.4 Wiring Requirements …………………………………………….. 7
3.5 Physical Characteristics………………………………………….. 8
3.6 Electrical Characteristics…………………………………………. 8
3.7 Mating Connector Information ……………..……………………. 8
3.8 Pinout Assignment Descriptions ………………………………... 9
3.9 Post-Installation Test …………………………………………….. 10
4.0 Troubleshooting Guide………………………………………… 10
4.1 General Troubleshooting Procedures ………………………….. 10
4.2 Troubleshooting ………………………………………………….. 10
5.0 Specifications …………………………………………………… 10
5.1 Unit Specifications ……………………………………………….. 10
6.0 Reference Drawings ……………………………………………. 11

Audio International, Inc. MSM2921-0x-x Installation
Document #540186, Rev. IR, 2/2000 Page 4 of 11
MODEL # MSM2921-0x-x
Discrete to RS485 Converter Module
1.0 General Information
1.1 Introduction
This manual contains information for the proper installation of the Audio
International, Inc. (AI) Discrete to RS485 Converter Module,
Model No: MSM2921-0x-x. The “-0x”in the model number designates the
internal firmware configuration of the unit. The “-x”in the model number
designates the type of connector utilized in installation. Also included are
physical and electrical characteristics of the unit.
1.2 Purpose of the Equipment
The MSM2921-0x-x provides the necessary medium to convert analog
serial communications to a discrete output via AI’s proprietary RS485
serial communication format and vice versa for means of providing an
interface to AI’s proprietary RS485 digital data bus.
Strapping pins are provided to enable the unit to address internal firmware
that will allow the operator and/or installation agency to use multiple
MSM2921-0x-x units on the same AI proprietary RS485 digital data bus.
1.3 Operational Features
Listed below are key features of the MSM2921-0x-x:
q 12 independent discrete switch inputs
q 12 independent discrete status outputs
q Software configurable per aircraft requirements
q Compact, lightweight
q Lightweight aluminum construction
1.4 Optional Equipment
Audio International, Inc. offers a comprehensive family of Cabin Control
Modules. These modules provide convenient solutions for a variety of
frequently encountered interfacing needs or special requirements and are
an important part of AI’s “building block”system for configuring total cabin
management.
Contact your AI representative for details.

Audio International, Inc. MSM2921-0x-x Installation
Document #540186, Rev. IR, 2/2000 Page 5 of 11
2.0 Application
2.1 Introduction
The MSM2921-0x is utilized in applications where momentary switch
contacts are required to interface with AI’s proprietary RS485 serial data
bus devices. The unit will allow for up to twelve (12) independent discrete
switch inputs and up to twelve (12) discrete status outputs for
communication on the data bus.
The strapping options allow the unit to address internal firmware to allow
the operator and/or installation agency to use multiple MSM2921-0x-x
controlled units on the same AI proprietary RS485 data bus.
2.2 Block Diagram –Typical Application
3.0 Installation
3.1 Prior to Installation
Prior to installation, the following items should be considered:
3.1.1 During the design and layout of the aircraft cabin, careful
consideration of the location of this module is necessary. Some of
the items to be considered include:
• Space
• Available power supply
• Environmental conditions (temperature, humidity, etc.)
• Length of cable runs

Audio International, Inc. MSM2921-0x-x Installation
Document #540186, Rev. IR, 2/2000 Page 6 of 11
3.1.2 The MSM2921-0x-x shall be installed to conform to the standards
designated by the customer, installing agency, and existing
conditions as to the unit location and type of installation.
3.1.4 Mounting screws are required to secure the unit. Refer to Section
6.0, Reference Drawings, for mounting hole diameters and
configuration.
3.2 Unpacking and Inspection
Carefully open the packaging and remove the unit. Verify that all
components have been included in the package per the packing list.
Inspect the unit for damage. Retain the packing materials and packing
list.
If damage has occurred during shipping, a claim must be filed with AI
within 24 hours and a “Return Request Authorization Number”must be
obtained from AI. Refer to the front cover of this manual for address and
telephone number of Audio International. Repackage the unit in its
original packaging materials and return it to AI following instructions given
by the AI representative. If no return is necessary, retain the packing
materials for storage or reshipment if necessary.
3.3 Cautions and Warnings
3.3.1 It is important to do a pin-to-pin power and ground check on all
connectors. Ensure that power and ground are applied only where
specified. Damage to the unit may result if power or ground is
applied to the wrong points.
3.3.2 DO NOT connect or disconnect the module while power is applied.
3.3.3 DO NOT remove any factory-installed screws. Damage to the units
may result and void any warranties.
3.3.4 ESD (Electro Static Discharge) guidelines shall be followed.

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.

Audio International, Inc. MSM2921-0x-x Installation
Document #540186, Rev. IR, 2/2000 Page 8 of 11
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 Two connectors are available on the MSM2921-0x-x. P1 is a 9-pin
connector that provides for power, ground, RS485 data bus
commands, and device ID strapping pins.
Device ID pins are used to provide a unique address on AI’s
proprietary RS485 serial data bus. These are binary ID pins and
will allow up to twelve (12) MSM2921-0x-x modules to be installed
on the aircraft’s AI proprietary RS485 serial data bus. If more than
one unit is configured on the data bus, connect the respective
device ID pins to ID common.
3.6.3 P2 is a 50-pin connector with provisions for up to twelve (12)
+28 VDC power outputs, twelve (12) switch contacts (momentary
ground in), twelve (12) status ground outputs, and twelve ground
outputs.
Each power and ground output is capable of driving up to 80 mA at
+28 VDC. The status outputs have the capability to sink up to
50 mA at +28 VDC. The power rating for the unit is 50 mA at
+28 VDC.
3.7 Mating Connector Information
All wiring harnesses to the unit are supplied and fabricated by the
installing agency.
Model # Pin # Mating Connector
MSM2921-0x-1 P1 RD9F10JVL0
P2 RD50M10JVL0
MSM2921-0x-2 P1 DEMA-9S
P2 DEMA-50P

Audio International, Inc. MSM2921-0x-x Installation
Document #540186, Rev. IR, 2/2000 Page 9 of 11
3.8 Pinout Assignment Descriptions
P1 P2
Pin # Description Pin # Description
1 +28 VDC 1 +28 VDC Output
2 Ground 2 +28 VDC Output
3 RS485 Data A 3 +28 VDC Output
4 RS485 Data B 4 +28 VDC Output
5 RS485 Data Bus Shield 5 +28 VDC Output
6 Strap ID 1 6 +28 VDC Output
7 Strap ID 2 7 +28 VDC Output
8 Strap ID 3 8 +28 VDC Output
9 Strap ID Common 9 +28 VDC Output
10 +28 VDC Output
11 +28 VDC Output
12 +28 VDC Output
13 #1 Switch Contact (MOM GND IN)
14 #1 Status Ground Out
15 #2 Switch Contact (MOM GND IN)
16 #2 Status Ground Out
17 #3 Switch Contact (MOM GND IN)
18 #3 Status Ground Out
19 #4 Switch Contact (MOM GND IN)
20 #4 Status Ground Out
21 #5 Switch Contact (MOM GND IN)
22 #5 Status Ground Out
23 #6 Switch Contact (MOM GND IN)
24 #6 Status Ground Out
25 #7 Switch Contact (MOM GND IN)
26 #7 Status Ground Out
27 #8 Switch Contact (MOM GND IN)
28 #8 Status Ground Out
29 #9 Switch Contact (MOM GND IN)
30 #9 Status Ground Out
31 #10 Switch Contact (MOM GND IN)
32 #10 Status Ground Out
33 #11 Switch Contact (MOM GND IN)
34 #11 Status Ground Out
35 #12 Switch Contact (MOM GND IN)
36 #12 Status Ground Out
37 N/C
38 N/C
39 Ground Output
40 Ground Output
41 Ground Output
42 Ground Output
43 Ground Output
44 Ground Output
45 Ground Output
46 Ground Output
47 Ground Output
48 Ground Output
49 Ground Output
50 Ground Output

Audio International, Inc. MSM2921-0x-x Installation
Document #540186, Rev. IR, 2/2000 Page 10 of 11
3.9 Post-Installation Test
Verify that the data bus conversion commences and appropriate
equipment is operational.
4.0 Troubleshooting Guide
4.1 General Troubleshooting Procedures
Many problems can be isolated with the following general techniques:
• To verify power to the unit, recheck +28 VDC is applied to the proper
pins on the unit. Use a voltmeter to verify correct level.
• Reset by removing power from the unit for at least one minute and
reapply power. Verify the problem still exists.
• Recheck all connections to the unit for security. Check all harness
runs for possible pinching. Recheck all pinouts for application
accuracy.
4.2 Troubleshooting
Should difficulties arise in the installation or operation of the unit, contact
AI Product Support for assistance.
5.0 Specifications
5.1 Unit Specifications
Physical Specifications
Housing Aluminum
Dimensions
(W x L x H) 5.71”x 5.40”x 1.05” 14.50cm x 13.72cm x 2.67cm
Weight 0.58 lbs / 0.26 kg
Electrical Specifications
Power 50 mA at +28 VDC
Data Bus Type AI Proprietary RS485
Outputs 80 mA at +28 VDC
Output Sink 50 mA at +28 VDC

Audio International, Inc. MSM2921-0x-x Installation
Document #540186, Rev. IR, 2/2000 Page 11 of 11
6.0 Reference Drawings
The following diagrams show the unit dimensions and connector locations for the
MSM2921-0x-x. All dimensions are shown in inches.