ARINC 748 : 1993

1.0 INTRODUCTION
1.1 Purpose of this Document
1.2 Relationship to Other Documents
1.3 System Description
1.3.1 Data System Architecture
1.4 Airborne Subsystem Configuration
1.5 Interchangeability
1.6 Software Partitioning
1.7 Regulatory Approval
2.0 INTERCHANGEABILITY STANDARDS
2.1 Introduction
2.2 Form Factors, Connectors and Index Pin
                Coding
2.3 Standard Interwiring
2.4 Primary Power Input
2.5 System Functions and Signal Characteristics
2.6 Environmental Conditions
2.7 Cooling
2.8 Grounding and Bonding
2.9 Standardized Signaling
2.9.1 ARINC 429 DITS Data Bus
2.9.2 Standard "Open"
2.9.3 Standard "Ground"
2.9.4 Standard "Applied Voltage" Output
2.9.5 Standard Discrete Input
2.9.6 Standard Discrete Output
2.9.7 Standard Program Pin Input
3.0 BASIC CMU CAPABILITIES
3.1 General Description
3.2 Basic CMU Functions
3.3 Internetworking Function
3.4 Network Management
3.5 Common Physical and Link Layer Interfaces
3.5.1 Physical Medium
3.5.2 Physical Layer
3.5.3 Link Layer
3.5.4 Network Layer
3.6 Air-ground Subnetwork Interfaces
3.6.1 VHF Communications
3.6.2 Satellite Communications
3.6.3 Mode S Communications
3.6.4 HF Communications
3.6.5 Gatelink Communications
3.7 Interfaces with Onboard Systems
3.7.1 ARINC 429 Data Words
3.7.1.1 Broadcast Transmissions
3.7.1.1.1 Subsystem Ident Word Definition
3.7.1.1.2 Active Functions Word Definition
3.7.1.1.3 LRU Identification Word Definition
3.7.1.1.4 ICAO Technical Address Word Definition
3.7.1.2 Broadcast Receive
3.7.2 ATN End Systems
3.8 Other Basic Functions
3.8.1 System Initialization
3.8.2 Loadable Routing Policy Database
3.8.3 ICAO Address Discovery
3.8.4 Data Loader Interface
4.0 OPTIONAL CMU CAPABILITIES
4.1 Introduction
4.2 Dual CMU
4.3 Applications
4.3.1 AOC Applications
4.3.2 ATSC Communications Applications
4.3.3 Application Flight Deck Interfaces
4.3.3.1 Multipurpose Control and Display Unit
4.3.3.2 Dedicated Control and Display
4.3.3.3 Multipurpose printer
4.4 Application Gateways
4.5 Onboard Avionics Local Area Network
4.6 ARINC 716 VHF Radio
4.6.1 Physical Layer
4.6.2 AVPAC Protocol
4.7 Data/Voice Mode Select
4.7.1 VHF Data Radio
4.7.2 ARINC 716 VHF Radio
4.7.3 Shared Transceiver Case
4.7.4 Dedicated VHF Transceiver
5.0 CMU ELECTRICAL INTERFACES
5.1 General Description
5.2 Primary Power Input
5.3 ARINC 429 Data Bus Interfaces
5.3.1 General Data Bus No. 1
5.3.2 General Data Bus No. 2
5.3.3 General Data Bus No. 3
5.3.4 General Data Bus No. 4
5.3.5 General Data Bus No. 5
5.3.6 General Data Bus No. 6
5.3.7 General Data Bus No. 7
5.3.8 General Data Bus No. 8A and No. 8B
5.3.9 OOOI Data Bus Inputs
5.3.10 Airborne Data Loader Data Buses
5.3.11 Digital Frequency Select Data Bus
5.3.12 CMU Crosstalk Data Buses
5.3.13 Digital Flight Data Acquisition Unit
                (DFDAU) Output Data Bus
5.3.14 UTC Clock Data Bus Output
5.3.15 User Defined Data Bus
5.3.16 Reserved Data Bus
5.4 Non-ARINC 429 Serial Buses
5.4.1 Control Unit Data Buses
5.4.2 Optional Auxiliary Terminal (OAT) Data Buses
5.4.3 Printer Data Bus Output
5.4.4 UTC 419 Data Bus Output
5.4.5 Flight Data Acquisition Unit (FDAU)
                Data Bus Input
5.5 Input Discretes
5.5.1 Captain/First Officer Identification
                Discrete Input
5.5.2 CMU Inhibit Discrete Input
5.5.3 Data Loader Discrete Input
5.5.4 FMC Active Port Select Discrete Input
5.5.5 ARINC 716 VHF Transceiver Voice/Data Mode
                Select Input
5.5.6 Voice Go-Ahead Alert Reset Discrete Input
5.5.7 Voice/Data Mode Monitor and Annunciator
                Discrete Inputs
5.5.8 OOOI Sensor Discrete Inputs
5.5.9 OAT RTS Discrete Input
5.5.10 OAT DTR Discrete Input
5.5.11 VHF Transmitter Voice PTT Discrete Input
5.5.12 Control Unit Suggested Spare No. 3 Discrete Input
5.5.13 Printer Status Discrete Inputs
5.5.14 User Defined Discrete Inputs
5.6 Output Discretes
5.6.1 Airborne Subsystem Failure Warning
5.6.2 "No Communications" Alert Discrete Output
5.6.3 CMU Active/STBY Discrete Output
5.6.4 Voice/Data Mode Annunciation Output
5.6.5 Remote Voice/Data Annunciation Output
5.6.6 Data Key Line Output
5.6.7 DFS Port Select Discrete Output
5.6.8 OAT CTS Discrete Output
5.6.9 OAT Uplink Indicator Discrete Outputs
5.6.10 MU Fault Discrete Output
5.6.11 CU Fault Discrete Output
5.7 Open/Short Contacts
5.8 Program Pin Assignment
5.8.1 Dedicated Transceiver Annunciation Program
                Input To Pin
5.8.2 Automatic/Manual Channel Changeover Program Pin
5.8.3 Voice Channel Frequency Control Program Pin
5.8.4 OOOI Sensor Input Program Pins
5.8.5 ICAO Address Program Pins
5.8.6 Aircraft Type Program Pins
5.8.7 SDI Program Pins
5.8.8 Registration Mark Program Pins
5.8.9 ICAO/Registration Mark Select Program Pin
5.8.10 716/750 Select Program Pin
5.8.11 Configuration Program Pin
5.8.12 Spare Program Pin
5.8.13 Program Pin Common
5.9 Unspecified Function User Defined Pins
5.10 Analog Input/Output Assignments
5.10.1 Audio In/Out from the 716 VHF Transceiver
5.10.2 716 VHF Transceiver Sidetone Input
5.11 ATE
6.0 PROVISIONS FOR TEST
6.1 Built-In Test Equipment
6.2 Fault Reporting
6.2.1 OMS Fault Reporting
6.2.2 Optional Character-Oriented BITE Fault
                Reporting
6.2.3 Optional Bit-Oriented BITE Fault Reporting
6.3 Automatic Test Equipment
6.3.1 ATE Testing
ATTACHMENTS
1-1 Aircraft-Ground Networks
1-2 CMU Protocol Architecture
2-1 Typical Single CMU Airborne Subsystem 429
                Data Bus Architecture
2-2 Typical Single CMU 429 Data Bus Architecture
                with 716 VHF
2-3 Typical Discrete and Program Pin Configuration
                with 716 VHF
3-1 CMU Rear Connector
3-2 CMU Interwiring
3-3 CMU Notes Applicable to the Standard Interwiring
3-4 Connector Insert Layout
4 CMU Environmental Test Categories
5 Deleted
6-1 Label 172 Word Definition
6-2 Label 270/271 Word Definitions
6-3 Maintenance Word Definitions
6-4 Label 377 Word Definition
6-5 Label 030 Word Definition
6-6 ICAO 24-BIT Address
APPENDICES
A Referenced Documents
B ACRONYM List

Contains the fit dimensions and physical form, the electrical interface definition and a description of the functional operation of the airborne Communications Management Unit (CMU). Provides general and specific design guidance for the development and installation of the CMU.