Honeywell Mark III User Manual

Technical Overview For

Mark III Communications
Management Unit (CMU)

23 July 2002

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1 INTRODUCTION

1.1 Mark III CMU Overview

Honeywell provides a family of Datalink products, ranging from the AFIS product for the business Jet market,
to our Mark II and Mark III CMUs for the Air transport and Military market. The Mark III Communications
Management Unit (CMU), discussed in this document, is Honeywell’s High-End “Next Generation” CMU.
The Mark III is a fully functional ARINC 758 CMU built using the latest hardware and software technology,
making it the most powerful and capable CMU in the industry today. Designed to exceed today's stringent
datalink requirements, the Mark III offers the capability to grow for tomorrow's rapidly expanding datalink
requirements.

The Mark III CMU is the next generation in CMU products. It offers over 100 Mbytes of memory (64 MB of
volatile memory and 48 MB of non-volatile memory). Utilizing a Pentium 266 MHz processor and 2 Power
PC dedicated I/O processors, the Mark III also offers a significant increase in processing power over other
CMUs in the industry. The dedicated I/O processors ensure the elimination of throughput bottlenecks
allowing the Mark III to concurrently process data from all data sources (today and in the future).

The Mark III CMU is a full ARINC 758 complaint unit, and is supported by an Aircraft Personality Module
(APM). In addition, the Mark III CMU contains additional I/O capability above and beyond that called out for
in the ARINC 758 characteristic. This includes a UHF Modem added to the unit for potential future use of
UHF as a datalink subnetwork. It includes customized RS 422 ports to support non-ARINC 739 CDUs that
are used on such aircraft as Embraer 135/145, and includes a PCMCIA interface for rapid dataloading. In
addition, the Mark III CMU has specifically been designed to support future modifications outside of the
ARINC 758 specification, to enable implementation of new technology that will provide additional benefits to
our airline customers. This expansion would be introduced using the current spare card slots designed into
the unit. The primary upgrade being planned is the introduction of an integrated Gatelink capability into the
unit, which would allow airlines to grow the CMU to support very high speed / short range communication
while on the ground using a 2.4 Ghz spread spectrum1 technology.

The baseline Mark III CMU provides the capability to communicate over HFDL, SATCOM, and VHF (Mode
0/A). By designing the Mark III CMU with the necessary hardware to support future datalink requirements,
functionality like VDL Mode 2 and the Aeronautical Telecommunications Network (ATN) are added with just
a software upgrade. Due to the size of the memory and processor capability contained within the unit, the
Mark III CMU provides the lowest risk to an airline for introduction of such new technology, as it becomes
required for future CNS/ATM operation.

The Mark III CMU utilizes a database-driven software architecture, which provides unparalleled flexibility. All
I/O parameters for an entire aircraft fleet are captured in a Flexible Input Data Base (FIDB). The Mark III
CMU then determines the aircraft type from the Aircraft Personality Module (APM) and applies the
appropriate set of I/O signals for that aircraft type.

A user has the capability to customize their Airline Operational Communications (AOC) application through
the use of the Airline Modifiable Information (AMI) database. All of the I/O parameters specified in the FIDB
are available to the user as part of the AMI definition. By having the I/O parameters isolated to the FIDB, a
single AMI can be subsequently generated using logical I/O parameters for all aircraft types within a fleet.
The AMI allows the user to:

• Design the screen layouts

1

The integrated Gatelink approach would provide on the order of a 1 to 11 Mbit/second network over approximately
1,000 feet utilizing the unlicensed 2.4 Ghz spread spectrum frequency. The Gatelink upgrade would also require a
TWLU and antennas to be installed on the aircraft, in addtion to a hardware upgrade to the Mark III CMU.

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• Define uplink and downlink message formats

• Define the format of printed messages

• Specify trigger logic (i.e., OOOI)

• Define the geographic area for specific frequency coverage

• Define the subnetwork preference by region

• Capture exceedances (mini-ACMS capability)

Once a user generates a new AMI, implementation is as simple as generating a disk containing the new
AMI database and using the Mark III CMU dataload capability to load the AMI into each aircraft with no
certification effort required.

The Mark III CMU also incorporates a new concept called the Honeywell Generated Information (HGI)
database. The HGI is a controlled database that contains protected information used by applications.
Typically, the HGI will contain protocol timers, ATC screen and printer formats, and ATC message
definitions. As with the AMI, all aircraft I/O parameters from the FIDB are available for use by the HGI.
Although changes to the HGI require a certification effort, no embedded operational software changes are
required.

Both the AMI and the HGI are generated using a common tool called the Ground Based Software Tool
(GBST). The GBST is a Windows-based application that allows the user to perform normal windowing
functions such as cutting and pasting components between the various GBST screens. The GBST is based
on the B-777 GBST, providing the same type of user interface as for the B-777, but providing increased
functionality available in the Mark III CMU.

1.2 Datalink Capability for Today and Tomorrow

Today, datalink users have found that datalink is an indispensable tool for helping manage operations,
maintenance and other functions. Datalink provides access to more data and timely data which results in
time and cost savings for an airline. Datalink users have found that datalink:

• Improves accuracy and efficiency of communicating with the flight crew

• Improves information dissemination within airline operations

• Provides timely availability of information

• Reduces delay times

• Reduces airline personnel effort (i.e., data courier, special services)

• Improves operational performance

• Reduces fuel costs

• Improves maintenance operation

• Improves passenger service

• Reduces pilot workload

The rapid expansion of datalink requirements has stretched the existing ACARS network toward capacity
and has accelerated the desire of datalink users to move away from the limited ACARS Management Unit
(MU) to the more capable Communications Management Unit (CMU).

The industry is demanding new approaches to meet the new requirements. Timely and accurate information
exchange between the aircraft and the ground is critical to an airline’s operation. Digital datalink
communications provides a method of moving that information to the right place at the right time, saving both

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time and money. However, to deliver the future datalink capability required by the airlines, both ground and
airborne systems must have a transition to the next generation architecture.

The Mark III CMU offers a datalink user the next generation ARINC 758 CMU capable of providing the
datalink functionality to meet the industry demands for today and tomorrow.

1.3 Honeywell Datalink Experience, Products, and Services

Honeywell has been developing Datalink Management Units since the early 1980s starting with the ARINC
597 ACARS. Since that time, Honeywell has continuously evolved and introduced new systems, comprised
of the 724 ACARS (introduced in 1988), the Mark I 724B ACARS (introduced in 1989), and the Mark II User
Re-programmable ACARS (introduced in 1991).

Honeywell currently offers two go-forward CMU products. The Mark II CMU is offered for 724B or 758 wiring
installations. The 965-0758-001 PN is for 724B installations, while the 965-0758-002 is for ARINC 758
installations. The other CMU is our new Mark III CMU (PN 7519200-920), which is offered for ARINC 758
wiring solutions2, and is described in this document.

Honeywell is the leading supplier of datalink systems, with over 100-datalink customers. This is significant
in light of the fact that at the beginning of the 1990s, Honeywell had only three customers. We contribute
this large growth due to the fact that we have continued to invest in datalink systems and technology. The
new Mark III is the latest in such product introductions.

Honeywell also developed the equivalent of an ACARS MU for the Boeing 777. This was the first dual and
integrated ACARS system and the first essential ACARS system.

Airbus uses a communications unit named the Air Traffic Services Unit (ATSU) which is designed and
manufactured by Aerospatiale. The ATSU is a Supplier Furnished Equipment (SFE) system but the AOC
applications software is provided as Buyer Furnished Equipment (BFE). Honeywell is the leading supplier of
ATSU AOC software, which is based on the same AOC software contained in the highly successful Mark II
CMU.

With our offering for the B-777, the ATSU and our CMU, Honeywell is the only manufacturer that can support
all three aircraft configurations.

Honeywell is also a leading supplier of datalink display systems. Whether it is a full-sized ARINC 739
MCDU, a compact ARINC 739 Multi-Input Display Unit (MIDU) or a compact CDU, there is a datalink display
system for all aircraft from air transport and regional to business jet and general aviation.

The Mark III interfaces with many avionics devices, particularly Flight Management (FM) systems.
Honeywell is the leading supplier of FMs, whether it is the advanced Pegasus platform in the air transport
arena or the NZ-2000 in the regional and business jet market. Honeywell also provides FM systems in its
integrated avionics solutions (AIMS, VIA, and Epic).

To complete a user's datalink capability, Honeywell also offers ARINC 740 cockpit printers, SATCOM, and
radio systems (HF and VHF).

In addition to datalink products, Honeywell offers supporting services. The Honeywell Global Data Center
(GDC) provides ground-based data services for users that do not wish to implement their own ground
infrastructure. GDC currently provides a turnkey solution for over 2,200 datalink equipped aircraft. This

2

The 7519200-920 part number reflects the standard Mark III CMU designed for ARINC 758 for air transport aircr aft.

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includes such services as Providing world-wide Weather messages to the aircraft, as well as being an FAA
approved distributor of messages such as Pre-Departure Clearances and ATIS. The Honeywell Aircraft
Maintenance and Operational Support System (AMOSS) provides ground ACARS message processing and
integration with flight planning systems. Finally, Honeywell provides world class product support worldwide.

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2 SYSTEM OVERVIEW

2.1 Hardware Overview

The Mark III CMU is based upon the Multiple Application Processing System (MAPS) platform which is the
new generation hardware that will be used for introduction of new Honeywell datalink products. This common
hardware platform will facilitate the introduction of communication products that integrate new capabilities
with the Mark III CMU.

The Mark III CMU is a single Line Replaceable Unit (LRU) housed in a standard 4 MCU ARINC 600 form
factor. The Mark III CMU contains 4 Circuit Card Assemblies (CCAs): (1) Processor; (2) I/O; (3) Power
Supply; and (4) Interconnect. There is expansion capacity for two spare CCAs.

The main processor is a 266 MHz Pentium while the I/O is handled by two MPC 860 microprocessors.
These two I/O processors are able to concurrently process all I/O effectively eliminating throughput
bottlenecks. Additionally, there are two dedicated digital signal processors (DSPs), one each for the VHF
and UHF modems. There is a total of 64 MB of DRAM along with 48 MB of Flash EPROM.

The front panel of the Mark III CMU (see Figure 1) contains a "PUSH TO TEST" button for initiating Test
Mode, two LEDs to indicate Test Mode Pass and Fail, an ARINC 615 connector, and a PCMCIA connector.
The ARINC 615 connector can be used for a portable data loader, a Debug and Maintenance Terminal

ARINC 615

(DMT), or for a Data Logging Terminal (DLT).

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Figure 1 Mark III CMU Front Panel

ARINC 607 defines the Aircraft Personality Module (APM) which contains all aircraft and system
configuration information. The APM is external to the MARK III CMU and is a permanent fixture in the
aircraft. Only one APM is required per MARK III CMU installation (one APM for each MARK III CMU
mounting tray). The same APM part number is used on all aircraft in the fleet.

2.2 System Interfaces

The Mark III CMU supports an extensive set of interfaces. Many of these interfaces are specifically defined
by ARINC 758. There are also a number of spare ARINC 429 ports available for additional devices as needed
by the user. The Mark III CMU supports all of today’s ACARS interfaces used on today’s aircraft, with
extensive capability for future growth.

Table 1 Mark III CMU Interfaces

PCMCIA

Device ARINC

Specificati

on

VHF Radio 716 Audio 1 Baseline
VDR: Mode 0

Mode A
Mode 2

Satellite Data Unit (SDU) 741

HF Data Radio (HFDR) 753 Low speed ARINC 429 2 Baseline
UHF --- Audio 1 Growth
Mode S Transponder 718A High speed ARINC 429 2 (note 7) Baseline
Gatelink 751

MCDU/MIDU 739 High speed ARINC 429 3 Baseline
DCDU undefined High speed ARINC 429 1/2 (note 5) Growth
CDU ---- RS-422 2 Baseline
Printer 740/744

FMC 702

Performance Computer (PZ) ----- RS-422 1 Growth
ACMS/DFDAU 619/429 Low speed ARINC 429 1 Baseline
CMC/CFDS/CFDIU 604/624 Low speed ARINC 429 1 Baseline
Cabin Terminal --- Low speed ARINC 429 2 Baseline
Electronic Library (ELS) --- High speed ARINC 429 1 Growth
Cockpit Voice Recorder
(CVR)
GPSSU 743 High speed ARINC 429 1 Baseline
APM 607 --- 1 Baseline
Dual CMU 758 High speed ARINC 429 1 note 6
Mil-Std-1553B --- Mil-Std-1553B 1 Growth
DMT --- RS-232 1 Baseline
DLT --- RS-232 1 Baseline
Airborne Data Loader 615 High speed ARINC 429 1 Baseline

750 Audio

761

undefined

744A

702A

757 Low speed ARINC 429 1 Growth

Interface # Baseline /

1
High speed ARINC 429
High speed ARINC 429
High speed ARINC 429
High speed ARINC 429

High speed ARINC 429

Ethernet 10BaseT

Low speed ARINC 429

Ethernet 10BaseT

Low speed ARINC 429

High speed ARINC 429

3

3

2

2 (note 1)

1

note 2

1 (note 3)

note 2
2/3 (note 4)
2/3 (note 4)

Growth

Baseline
Baseline

Option

Baseline

Growth

Growth
Growth

Baseline (note 3)

Growth

Baseline

Growth

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Portable Data Loader 615 High speed ARINC 429 1 Baseline
Ethernet Data Loader 615A Ethernet 10BaseT note 2 Growth
PCMCIA --- PCMCIA 1 Baseline

Notes:

1. Supports up to 2 total SDUs, whether ARINC 741 or 761.

2. The Mark III provides 4 10BaseT Ethernet ports which can be used for any purpose.

3. Supports 1 ARINC 740/744 printer in baseline. An additional printer can be added to one of the spare
ARINC 429 ports. This requires a software upgrade.

4. Supports 3 FMCs in the AT & Mil products.

5. Supports 2 DCDUs in the AT & Mil products and 1 DCDU in the BRH product

6. The Baseline Mark III supports Cold Spare operation. A software upgrade would be required for
additional dual capability.

7. The Mark II CMU interfaces with the transponder to obtain the ICAO address

2.2.1 Subnetwork Interfaces

The Mark III CMU supports a complete set of ARINC 758 subnetwork interfaces (see Figure 2).

ARINC 750

ARINC 750

VDR

ARINC 750

VDR

VDR

SDU

SDU

HFDR

HFDR

ARINC 716

Radio

ARINC 716 VHF Radio

The Mark III CMU supports an interface with one ARINC 716 VHF radio. The interface supports VDL Mode 0,
via an audio line to the Minimum Shift Keying (MSK) modem resident in the Mark III. There is also a low
speed ARINC 429 transmit interface between the CMU and the ARINC 716 radio that is used to send
frequency tuning information.

ARINC 750 VHF Data Radio (VDR)

The Mark III CMU can interface with up to three ARINC 750 VDRs. The Mark III supports the operation of a
VDR operating in ARINC 716 mode by utilizing the same audio line as used for an ARINC 716 radio. The
CMU also supports a high speed ARINC 429 interface to the VDRs for VDL Mode A.

VDL Mode 2 will utilize the same high speed ARINC 429 interface as VDL Mode A, allowing growth to VDL
Mode 2 with just a software upgrade. VDL Mode 2 offers an increase of throughput from 2.4 kbps to 31.5
kbps. VDL Mode 2 is necessary both for ATN communications and for ACARS Over AVLC (AOA). VDL
mode 2 is offered as an optional software package for the Mark III CMU.

Mark III

CMU

Gatelink

Figure 2 CMU Subnetworks

UHF

Mode S

Mode S

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Satellite Communications (SATCOM)

The Mark III CMU can be configured to interface with one or two ARINC 741 compliant Satellite Data Units
(SDUs) via low speed ARINC 429, or can be configured for high speed 429.

The industry is still working on the definition of the ARINC 761 specification for second generation satellite
communications systems, which will include access to Low Earth Orbit (LEO) and Medium Earth Orbit
(MEO) satellite constellations. When datalink communications over ARINC 761 subnetworks is fully defined,
it is planned that the Mark III will be updated (software only) to accommodate both ARINC 741 and ARINC
761 satellite communications.

HF Data Radio (HFDR)

The Mark III CMU can be configured to interface with one or two ARINC 753 compliant HFDRs (or HF Data
Units -- HFDU) via low speed ARINC 429. The HFDR offers a datalink user another datalink option when line­of-site VHF and satellite communications are not available (i.e., over the ocean or poles).

UHF

The Mark III CMU contains a UHF modem to support UHF datalink. Software support of this interface
requires a software upgrade. Currently there are no interfaces used with datalink for UHF, but the hardware
has been added into the baseline unit to support potential future capability.

Mode S Transponder

The Mark III CMU can be configured to interface with one or two Mode S Transponders via high speed
ARINC 429. Currently, datalink operation over Mode S is not defined. However, the Mark III CMU has the
necessary ARINC 429 receivers in place to support such future need, if ever required. It should be noted that
the Mark III CMU baseline does include the interface to the Mode S in order to obtain the ICAO 24 character
address (which is then used for verification of data in the APM).

Gatelink

The current ARINC 758 specification identifies an ARINC 429 interface for gatelink interfaces. This is
supported by the Mark III CMU hardware. However, Ethernet 10BaseT is a more likely Gatelink interface.
The Mark III CMU supports up to four 10BaseT Ethernet ports. Honeywell will be offering a future upgrade
package to the Mark III CMU that supports Gatelink capability within the unit, interfacing directly with a
TWLU (Gatelink - Transceiver Wireless LAN Unit).

2.2.2 Flight Deck Devices Interfaces

The Mark III CMU supports interfaces to the following flight deck devices: (See Figure 2.2.2-1 for the
available Datalink display devices supported by the Mark III CMU).

Multi-purpose Control and Display Unit (MCDU) / Multi-Input Display Unit (MIDU)

The Mark III CMU can be configured to interface with up to three ARINC 739 compliant display devices.
These devices could be a standard MCDU or the compact MIDU. This is the standard interface on all Boeing
/ Airbus and many other types of aircraft. The Mark III CMU supports the ability to present different menus
simultaneously on different displays, providing a high degree of flexibility to the flight crew.

Dedicated Display and Control Unit (DCDU)

The industry envisions that certain ATS Datalink Services will require a dedicated datalink display device
mounted in the primary field of view. The Mark III CMU can be configured to interface with one or two DCDUs
via high speed ARINC 429. Software support for these devices is likely to be available through a software­only upgrade once the definition of this interface is fully defined by the industry.

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Control and Display Unit (CDU)

Figure 2.2.2-1

Datalink Display Units

In the business jet and regional aircraft market place, there is limited cockpit pedestal real estate. Often,
these aircraft are equipped with a 4-line-select key CDU instead of a 6-line-select key MCDU. The Mark III
CMU can be configured to interface with one or two of these CDU devices via an RS-422 interface.

MCDU

MCDU

CDUMIDU

Printer

The Mark III CMU can interface with a single ARINC 740 or 744 compliant printer via low speed ARINC 429.
This includes Honeywell’s ARINC 740 printer, as well as all other manufacturer’s who support the ARINC
740/744 specification.

ARINC 744A defines an Ethernet printer interface. The Mark III CMU has available Ethernet ports but
requires a software upgrade to support an ARINC 744A printer. Currently, there are no aircraft configurations
defined using the Ethernet interface for the CMU to printer interface.

Crew Alerts

The Mark III CMU provides the interfaces necessary to support aural and visual alerts as well as an
indication of NO COMM.

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Figure 4 Cockpit Printer

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2.2.3 LRU Interfaces

In general, the Mark III CMU can support any LRU that uses the ARINC 429 File Data Transfer Protocol or
Williamsburg Protocol to communicate as an end system, as defined in ARINC 619 (ACARS file transfer
protocols for other devices). ARINC 758 identifies a number of specific LRUs and the Mark III CMU supports
interfaces to these LRUs:

Flight Management Computer (FMC)

The Mark III CMU can be configured to interface via low speed ARINC 429 with up to three ARINC 702
compliant FMCs operating as end systems. The Mark III CMU can alternatively be configured to interface
with up to three ARINC 702A FMCs over high speed ARINC 429. The Mark III CMU can also accept ARINC
429 broadcast data from the FMCs. This broadcast data provides the CMU with data that is captured in the
FIDB and available for use by the HGI and AMI.

Performance Computer (PZ)

In some aircraft installations, there is a separate performance computer (PZ) in addition to an FMC. The
performance computer communicates with a CDU through the CMU (See Figure 5) via RS-422. The Mark III
CMU can support a single interface to a performance computer with a software upgrade.

RS-422 RS-422

Performance
Computer

Mark III
CMU

CDU

NZ-2000

Figure 5 CMU/PZ Pass Through Interface

Maintenance Computer

The maintenance computer name varies depending upon the Original Equipment Manufacturer (OEM) but is
usually referred to as the Central Maintenance Computer (CMC), Centralized Fault Display System (CFDS),
or Central Fault Display Interface Unit (CFDIU). The Mark III CMU can be configured to interface with one
maintenance computer over low speed ARINC 429. This interface supports both end system
communications as well as the maintenance computer protocol.

The maintenance computer protocol varies based upon airframe. The Boeing 747 uses broadcast fault bits
while most other air transport aircraft (e.g., MD-10, MD-11, B-717, A-320, A-330, A-340) use an interactive
data block transfer utilizing MCDU screens. Other aircraft types do not currently support maintenance
computers (e.g., MD-80, MD-90, B-737, B-757, B767, regional and business jets). The baseline Mark III
CMU supports the broadcast fault bits. Interactive data block transfer protocol will be available as a planned
upgrade.

Aircraft Condition Monitoring System (ACMS)

The Mark III CMU can be configured to interface with a single Aircraft Condition Monitoring System (ACMS)
or Digital Fault Data Acquisition Unit (DFDAU) via low speed ARINC 429. This interface supports end
system communications using the standard ARINC 619 protocol in addition to providing the CMU access to

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an extensive amount of ARINC 429 broadcast data providing aircraft performance related data. All of the
ARINC 429 broadcast data is available via the FIDB to be used by both the HGI and the AMI.

Cabin Terminal

The Mark III CMU can be configured to support up to two Cabin Terminals operating as end systems.

Electronic Library System (ELS)

Although there are no ELS systems in use today which interface to CMUs, the Mark III CMU can be
configured in the future to interface with a single ELS operating as an end system via high speed ARINC

429.

Cockpit Voice Recorder (CVR)

The industry is developing ARINC Specification 757 which defines a Cockpit Voice Recorder or Digital Data
and Voice Recorder (DDVR) capability. The Mark III CMU provides a single low speed ARINC 429 interface
that can be used to interface with an ARINC 757 compliant device. This capability will require a software
upgrade.

Global Positioning Satellite System Unit (GPSSU)

The Mark III CMU can accept high speed ARINC 429 broadcast data from ARINC 743 compliant GPSSU(s).

2.2.4 Other Interfaces

The Mark III CMU also supports the following interfaces:

Aircraft Personality Module (APM)

ARINC 607 defines the characteristics of an Aircraft Personality Module which contains aircraft and system
configuration information and makes this information available to the CMU. The Mark III CMU supports a
single interface to an ARINC 607 compliant APM.

Dual CMU

The Mark III CMU is capable of operating in either a standalone or dual configuration. The Mark III CMU
hardware includes interfaces to support dual CMU operation. The interface between the onside and offside
CMUs is via a high speed ARINC 429 cross-talk bus along with discretes that indicate active and standby
states.

In a dual CMU configuration, the left CMU is normally considered the Active unit and the right CMU is
normally considered the Standby unit. The Active CMU is the one that communicates with the subnetworks.

There are three possible dual CMU configurations; cold spare, warm spare, and hot spare.
The Cold Spare Configuration is the configuration in which the two CMUs on the aircraft do not communicate

datalink information with each other. In the event of a failure of the Active CMU, the Standby CMU must be
manually configured (via a cockpit switch) to be the Active CMU.

The Warm Spare Configuration is the configuration in which the two CMUs exchange datalink information.
In the event that a fault occurs in the Active CMU, the Standby CMU will automatically be configured as the
Active CMU.

The Hot Spare Configuration is the configuration in which the Standby CMU is monitoring all configuration
and traffic so that it can seamlessly assume the role of Active CMU in case of a failure of the Active CMU.

The baseline Mark III CMU supports cold spare operation. Other dual operations are waiting on industry
definition. The ARINC Datalink Subcomittee is planning on updating the ARINC 758 characteristic in the

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future to define Warm and Hot spare requirements. This effort has not yet started. As the Mark III CMU
hardware was designed to support Dual capability, Updated dual capability could be provided with a software
upgrade.

Ethernet

ARINC 646 defines an Ethernet Local Area Network (ELAN) aboard an aircraft. The Mark III CMU provides
four 10BaseT Ethernet ports that can be used for various applications which could include Gatelink
connectivity, ARINC 615A data loading, ARINC 744A printer and ELAN connectivity. Software support for the
Ethernet ports will require a software upgrade.

MIL-STD-1553B

Mil-Std-1553B is a military standard interface used to communicate with onboard end systems such as an
FMC, MCDUs and remote annunciators. This hardware interface is only available in the military version of
the Mark III CMU. Software support of this interface requires a software upgrade. This is applicable for only
specific Military aircraft.

Debug Maintenance Terminal (DMT) / Data Logging Terminal (DLT)

A Debug Maintenance Terminal and Debug Logging Terminal can be used to access BITE information,
program the APM, and for general debug capability. The Mark III CMU provides two RS-232 ports that can
be used for a DMT and a DLT. The RS-232 ports are accessible both from the front and rear connectors and
can interface with a laptop computer executing terminal emulation software. The DMT is a device that is
used for Honeywell debugging and testing, and is not a device required by our airline customers.

Data Loader

The Mark III CMU supports an interface to both an ARINC 615 compliant Airborne Data Loader (ADL) and an
ARINC 615 compliant Portable Data Loader (PDL) via high speed ARINC 429. The ADL interface is
accessible through the rear connector while the PDL is accessible from the front connector.

High speed data loading via PCMCIA and Ethernet are software growth options.

PCMCIA

The Mark III CMU hardware is equipped with a PCMCIA interface that can be used, to provide a faster
means of data loading than an ARINC 615 data loader. The PCMCIA interface is accessible only from the
front panel. PCMCIA is Honeywell’s recommended method of performing complete full software loads.

OOOI

The Mark III CMU provides up to 6 high speed ARINC 429 inputs and a number of analog discrete inputs that
can be used to determine Out/Off/On/In events. Data available on these interfaces typically include oil
pressure, weight on wheels (WOW), flaps, parking brake, and doors.

2.3 Software Overview

In order to meet the system/safety requirements of future CNS/ATM upgrades, all of the Mark III CMU
software has been developed to support a future DO-178B Level C. Today, the Mark III CMU is certified to
Level D, which is the standard used for certification of ACARS and CMU units. Partitioning in the Mark III
CMU is supported by the DEOS operating system which has been previously certified to DO-178B Level A.

The underlying fundamental goal for the Mark III CMU software development was to develop a single software
system that could be used with minor modification on other platforms. Honeywell was able to achieve this
goal through the use of advanced software development techniques, including model-based development.
The model-based approach allowed the developers to design the system independent of the target hardware,
capturing the requirements in a model database. The requirements/design are then turned into source code

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through an automated code generation system specific to the target environment. Automated test scripts

VIA

are also derived from the model database. (See Figure 6).
The software architecture was developed to isolate target-specific components from the core software

components. The combination of the model-based approach and isolating target-specific components
allowed Honeywell to develop a Communications Management Function (CMF) that can be readily hosted
on other hardware targets including the Honeywell integrated platforms VIA and Epic (and in the future B-777
AIMs). This common communications function allows Honeywell to maintain a single communications
baseline across platforms, ensuring consistent implementations. This is beneficial to an airline that may
have a mixed fleet containing both federated and integrated architecture aircraft. A prime example is the
Embraer regional jet family. The Honeywell standalone Mark III CMU has been selected by many airlines for
their ERJ-135 and ERJ-145 aircraft. The next generation ERJ-170 and ERJ-190 contain the Primus Epic
integrated avionics cockpit which includes the CMF. Although the Mark III CMU and the Primus Epic are
different hardware platforms, the same core CMF capability exists on both platforms.

Mark III

CMF

Target-specific

Epic

Figure 6 Communication Management Function (CMF) for Both Federated and Integrated

Platforms

Another driving goal of the software architecture was to provide as flexible a system as possible by utilizing
a database-driven design. This design approach allows quick and easy changes to the Mark III CMU without
modifying the embedded operational software. (See Figure 7).

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CMU

AOC

HGI AMI

FIDB

GBST

Figure 7 Database Design

The Flexible Input Data Base (FIDB) contains a list of all I/O parameters available for all aircraft within a
fleet. The FIDB contains information regarding LRU source, data busses, labels, scaling, and resolution for
each I/O parameter.

The Airline Modifiable Information (AMI) database is generated by the user to customize their AOC
application. AOC screen and print formats, message definitions and trigger logic can all be specified in the
AMI. Changes to the AMI only require a dataload operation but no certification activity. This is a significant
change from pervious systems, such as our Mark II CMU and competitors CMUs, which still maintain much
of this processing within an AOC software segment. With the Mark III CMU, all such functionality is
contained within the AMI, providing airlines significantly more control and flexibility for performing changes,
as requirements change.

The Honeywell Generated Information (HGI) database provides capability similar to the AMI, but for protected
data typically used by ATC applications. Unlike the AMI, HGI changes require certification although no
change to the embedded operational software.

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2.4 Certification

Honeywell received the 1st FAA certification in December 2001. This initial certification was for Embraer
aircraft. The Mark III CMU has since also been type certified by Boeing. Contact Honeywell for up-to-date
information on other certifications completed or in work.

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3 FUNCTIONAL OVERVIEW

The Mark III CMU is designed to provide complete datalink capability, providing interfaces and support to
today’s installed equipment. In addition, Honeywell as well as the industry recognizes that Datalink features
will be expanded over time, and is in fact the principle behind the current ARINC 758 characteristic. A
Characteristic that was developed to define current operation (referred to as Level O.1A), and allow
expansion over time to support new requirements and needs. The Mark III CMU was specifically designed to
support such future growth. Growth Functionality describes potential new capabilities for post-baseline
software releases. Many of the capabilities described in both the Baseline Functionality and Growth
Functionality sections are configurable via the AMI or the HGI.

The Mark III CMU supports an ARINC 739 MCDU, an ARINC 739 MIDU, and a CDU for displaying ACARS
information. For the purpose of simplifying the text of this section, 'datalink display' will be used generically
to mean MCDU, MIDU, or CDU.

3.1 Baseline Functionality

The baseline Mark III CMU provides functionality defined as level 0.1A in ARINC 758.
For Reference, the level of functionality as defined in the ARINC 758 Characteristic is shown below. This

level of functionality is defined, as the CMU is recognized within the industry as evolving over time in order to
meet future CNS/ATM requirements.

A758 level Service Function

0 ARINC 724B ACARS equivalent

ARINC 618: ACARS
ARINC 716: VHF
ARINC 750: VHF Mode 0
ARINC 741: SATCOM

0.1 + VDR Mode A using ARINC 429 I/F
ARINC 750: Mode A
ARINC 761: SATCOM
ARINC 753: HF

0.2 AOA VDLM2

1 + ATN Services

ARINC 750: VDL Mode 2

2 + High Speed Services

Not specified at this time

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