User's Manual

SYSTEM DESCRIPTION, INSTALLATION, AND MAINTENANCE MANUAL
ARINC 781-200 SDU and SCM
23-15-30 1-8
DATE TBD
The major interfaces of the SDU are listed in Table 1-4.
B. SCM
The SCM does not provide any interfaces other than a dedicated interface to the SDU.
The SCM is powered by the SDU.
5. User Interfaces
This section describes the A781-200 SDU interfaces that enable users to access Inmarsat
services and monitor the operation of the A781-200 system.
NOTE: There are no user interface associated with the SCM.
A. MCDU
The MCDU is a device that uses an ARINC 429 interface per ARINC 739, which lets you
communicate with individual instruments on an aircraft, including the Flight Management
System (FMS), very high frequency (VHF) radio, and the SDU.
The SDU supports three MCDUs.
B. 4-Wire Audio
The SDU supports two 4-wire audio interfaces.
C. Ethernet
The SDU supports one Ethernet data interface.
Table 1-4 SDU System Interfaces
System Interface Description
ACU/BSU (x1) Antenna Control Unit/Beam Steering Unit
MCDU (x3) Multi-Purpose Control and Display Unit
ACARS CMU (x2) Aircraft Communication Addressing and Reporting System
Communication Management Unit
IRS (x2)/GPS (x1) Inertial Reference System/Global Positioning System
SCM (x1) SDU Configuration Module
AES ID (x1) Aircraft Earth Station Identification
Servicing Front Panel Accessible Service Port for data log retrieval
Button Initiated Self-Test
RF Transmit/receive to the DLNA
Antenna subsystem ARINC 781 Antenna Subsystem
Miscellaneous ARINC discrete input, outputs, and configuration straps