1、CONSIDERATIONS FOR AVIONICSNETWORK DESIGNARINC REPORT 428PUBLISHED: OCTOBER 9, 1995AN DOCUMENTPrepared byAIRLINES ELECTRONIC ENGINEERING COMMITTEEPublished byAERONAUTICAL RADIO, INC.2551 RIVA ROAD, ANNAPOLIS, MARYLAND 21401Copyright 1995 byAERONAUTICAL RADIO, INC.2551 Riva RoadAnnapolis, Maryland 21
2、401-7465 USAARINC REPORT 428CONSIDERATIONS FOR AVIONICSNETWORK DESIGNPublished: October 9, 1995Prepared by the Airlines Electronic Engineering CommitteeReport 428 Adopted by the Airlines Electronic Engineering Committee: July 31, 1995Report 428 Adopted by the Industry: August 30, 1995FOREWORDActivit
3、ies of AERONAUTICAL RADIO, INC. (ARINC)and thePurpose of ARINC Reports and SpecificationsAeronautical Radio, Inc. is a corporation in which the United States scheduledairlines are the principal stockholders. Other stockholders include a variety of otherair transport companies, aircraft manufacturers
4、 and foreign flag airlines.Activities of ARINC include the operation of an extensive system of domesticand overseas aeronautical land radio stations, the fulfillment of systems requirementsto accomplish ground and airborne compatibility, the allocation and assignment offrequencies to meet those need
5、s, the coordination incident to standard airbornecommunications and electronics systems and the exchange of technical information.ARINC sponsors the Airlines Electronic Engineering Committee (AEEC), composedof airline technical personnel. The AEEC formulates standards for electronicequipment and sys
6、tems for airlines. The establishment of Equipment Characteristicsis a principal function of this Committee.It is desirable to reference certain general ARINC Specifications or Reportswhich are applicable to more than one type of equipment. These general Specificationsor Reports may be considered as
7、supplementary to the Equipment Characteristics inwhich they are referenced. They are intended to set forth the desires of the airlinespertaining to components or equipment is concerned.An ARINC Report (Specification or Characteristic) has a twofold purposewhich is:(1) To indicate to the prospective
8、manufacturers of airline electronic equipment theconsidered opinion of the airline technical people coordinated on an industrybasis concerning requisites of new equipment, and(2) To channel new equipment designed in a direction which can result in themaximum possible standardization of those physica
9、l and electricalcharacteristics which influence interchangeability of equipment withoutseriously hampering engineering initiative.iiARINC REPORT 428TABLE OF CONTENTSITEM SUBJECT PAGE1.0 INTRODUCTION 11.1 Purpose and Scope 11.2 Document Precedence 11.3 Global Data Communication Environment 11.3.1 Dat
10、a Flow 11.3.1.1 Internal Data 11.3.1.2 External Data 11.4 Document Overview 12.0 AVIONICS SYSTEM ARCHITECTURES 32.1 Architectural Considerations 32.1.1 Reliability 32.1.2 Maintainability 32.1.3 Capacity/Rate 32.1.4 Integrity 32.1.5 Determinism 32.1.6 Degree of Integration 32.1.7 Cost Effectiveness 3
11、2.1.8 Weight 32.1.9 Application of Commercial-Off-The-Shelf (COTS) Software 32.1.10 Growth 32.1.11 Compatibility with Existing Systems 42.1.12 Security 42.1.13 Availability 42.1.14 Media Flexibility 42.1.15 Technology Maturity 42.2 Standard Buses Versus Private Buses 43.0 AVIONICS FUNCTIONAL CONSIDE
12、RATIONS 53.1 Avionics Communications 53.2 Flight Critical Functions 53.3 Essential Functions 53.4 Data Link Functions 53.5 Other Functions 54.0 AVIONICS NETWORK DEFINITION 64.1 Network Objectives 64.1.1 Rating Objectives 64.1.2 Customizing Objectives 64.2 Services 64.2.1 Data Transfer Services 64.2.
13、1.1 Transfer Types and Mechanisms 64.2.1.2 Access Mechanisms 64.2.1.3 Addressing 64.2.1.4 Representation of Data 74.2.2 Network Operation and Control Services 74.2.2.1 Debug and Integration Support 74.2.2.2 Status and Event Notification 74.3 Quality 74.3.1 Availability 74.3.2 Errors 74.3.2.1 Effects
14、 on Address, Data and Control Entities 74.3.2.2 Response(s) to Errors 74.3.3 Built-In-Test (BIT) 74.4 Capacity 74.4.1 Number of Clients 74.4.2 Number of Interfaces 74.4.3 Address Space 74.4.4 Message Size 84.4.5 Speed 8iiiARINC REPORT 428TABLE OF CONTENTS (contd)ITEM SUBJECT PAGE4.4.5.1 Throughput 8
15、4.4.5.2 Latency 84.5 Architecture Support 84.5.1 Redundancy 84.5.2 Fault Containment 84.5.3 Determinism 84.5.4 Synchronization (Inter-Network) 84.5.5 Central Resource(s) 84.5.6 Hooks 84.6 Issues 84.6.1 Tenure Length/Arbitration Frequency 84.6.2 Maintenance 84.6.3 Diagnostics and Test 94.6.4 Hot Inse
16、rtion 94.6.5 Validation and Verification 94.7 Constraints 94.7.1 Cost 94.7.2 Packaging 94.7.3 Connectors 94.7.4 Physical Constraints 94.7.4.1 Component Placement 94.7.4.2 Drop Spacing (Minimum, Maximum) 94.7.5 Electrical Characteristics 94.7.6 Electromagnetic Environment 94.7.7 Power Supply 94.7.8 M
17、issing Nodes, Open Drops 9APPENDICESA Glossary 10ivARINC REPORT 428 - Page 11.0 INTRODUCTION1.1 Purpose and ScopeThe purpose of this document is to provide the frameworkfor developing a compilation of requirements for anairplane-wide avionics network. This document isintended to provide system-level
18、 considerations for thedevelopment of such a network. The avionics networkmay include a mix of standard data buses and private databuses.This document is written for the “avionics networkdeveloper“ involved with the systems engineering processand the selection of existing data standards and protocol
19、sfor use in an airborne environment. It presumes thatexisting standards such as ARINC Specification 429 andARINC Specification 629 will be considered in thenetwork definition.This document applies to the digital data communicationbetween identifiable sources and sinks that include, but arenot limite
20、d to Line Replaceable Units (LRUs), LineReplaceable Modules (LRMs), and Integrated ModularAvionics (IMA) cabinets on a single airplane. Otherresources such as power distribution, cooling, mechanicalsupport are outside the scope of this document. However,this document may affect the definition of tho
21、se resources.This document represents a top-down approach for theselection of data bus and protocol standards applied to anavionics network. As a secondary role, this document isexpected to be useful in the development of AEECstandards for data communication. This includes data busstandards, protoco
22、l standards and, where applicable,network standards. It establishes the criteria for selectingproven data communication standards used elsewhere inthe electronics industry that meet the expectations ofairline users. Depending on the type of avionicsapplication, the resulting network may fully or onl
23、ypartially refer to existing data communication standardsand protocol definitions. These standards describe thephysical layer, data link layer and the appropriate elementsof the network layer of the Open Systems Interconnect(OSI) reference model published by the InternationalOrganization for Standar
24、dization (ISO).For instance, for deterministic flight critical data transfers,a communication stack that is less complex than the OSIstack may be preferred, and a specific upper layer protocolmay be developed. Where compatibility with the OSIstandards is needed (i.e., for air to groundcommunications
25、) the full OSI stack may be used. Bothapproaches could be implemented at the same time on agiven network, different stacks would be used for differenttypes of exchanges.The functions to be performed by upper layers of the OSIreference model are defined in ARINC Specification 638,“OSI Upper Layer Spe
26、cification.“ ARINC Specification638 refers to numerous ISO documents that pertain to theOSI reference model.1.2 Document PrecedenceA significant amount of industry discussion preceded thedevelopment of ARINC Report 428. One common threadin those discussions was the desire for data busstandardization
27、 and the associated need to minimize theproliferation of data bus standards.A secondary concern was the historic tendency for theindustry to develop a data bus standard without fullyunderstanding the breadth of applications. This documentwas written to ensure that new data bus standards will bedevel
28、oped when there is a demonstrated need.This Report represents a disciplined thought process thatan avionics engineer should apply prior to thedevelopment of an avionics network. The document isunique in the sense that it deliberately refrains fromoffering hard specification or even guidance. Rather,
29、 itidentifies the issues that the network developer shouldconsider and the parameters that should be specified aspart of the systems engineering process.1.3 Global Data Communication EnvironmentThe avionics network developer is expected to be familiarwith the global data communication environment th
30、at ispart of the airlines infrastructure.The avionics network is expected to take intoconsideration the expected volume and format of digitalmessages being sent to/from these systems.1.3.1 Data FlowAircraft operators are concerned with efficient data flowbetween avionics equipment and assurance that
31、 there isadequate margin to add equipment without severelyimpacting a data bus or the network in which theequipment operates. A network should be viewed as atool to transfer the necessary data on the airplane.1.3.1.1 Internal DataInternal data is defined to be data originating from asystem onboard t
32、he airplane. An example is weather radardata sent from the transceiver to a cockpit display.1.3.1.2 External DataExternal data is defined to be data originating fromsystems outside the airplane. An example is data linkinformation.1.4 Document OverviewSection 1 is an introduction to this document. It
33、 includesthe description and expected application of this document.Section 2 describes the role of avionics architecture in thedefinition of an avionics network.Section 3 describes the types of avionics functions that usethe avionics network.Section 4 is the summary of objectives that should beconsi
34、dered for an avionics network.ARINC REPORT 428 - Page 21.0 INTRODUCTION (contd)1.4 Document Overview (contd)Avionics network considerations can been divided into thefollowing main categories:Services The services that are to be providedby the networkQuality The quality of those servicesCapacity Para
35、meters that quantify the servicedelivery capacityArchitecture Application-specific system structuralSupport needsIssues Non-structural application-specificneedsConstraints Parameters that bound the designspaceSection 4 is structured according to these categories.Appendix A is a glossary of definitio
36、ns that are providedto support this document.ARINC REPORT 428 - Page 32.0 AVIONICS SYSTEM ARCHITECTURES2.1 Architectural ConsiderationsThe principles for defining an avionics network are largelyinfluenced by the underlying avionics architecture. Thenetwork definition may include the selection of pro
37、vendata communication standards and protocols usedelsewhere in industry.This section identifies the architectural considerations thataffect the definition of an avionics network. Theseconsiderations have been identified as important to theairline operators, airframe manufacturers, and avionicsequipm
38、ent suppliers in the overall performance of anetwork.COMMENTARYEach consideration describes an architectural issueand how it influences the avionics network definition.The issues are described at a high level for thepurpose of deriving the objectives in the followingsections of the document. There a
39、re no specificobjectives stated in these sections, only designconsiderations. Airline users expect to be consultedin developing the requirements that represent theoperational characteristics of the airplane and impacton definition of a network.It is recognized that even the most efficient networkcan
40、not compensate for deficiencies in an avionicsarchitecture. Therefore, the network developer isencouraged to work in concert with avionics systemengineers developing the underlying architecture.2.1.1 ReliabilityThe avionics network is a global resource on the airplane.Its reliability should support
41、the reliability goals of thefunctions using the network. It should also positivelycontribute to the overall reliability of the system.Airlines expect avionics equipment and avionics networkreliability to be commensurate with scheduled maintenanceactivities for engines, structures, etc.2.1.2 Maintain
42、abilityThe maintenance activities associated with the networkshould be minimal. The routine maintenance activitiesshould be consistent with airline maintenance practices.The network should positively contribute to themaintenance activities of the aircraft. It should providestatus reporting and diagn
43、ostic capability.2.1.3 Capacity/RateThe avionics network should be able to accommodate,with minimal hardware changes, the anticipated data flowfor all avionics equipment (i.e., aircraft systems) andexternal data communication (i.e., data link). The networkshould provide adequate flexibility to accom
44、modatevarious system architectures. Equipment upgrades shouldhave minimal impact on the network.2.1.4 IntegrityAirworthiness regulations, level of criticality andavailability goals influence the degree of integritynecessary. The avionics network should support theairworthiness integrity requirements
45、 of the system it isintended to support.2.1.5 DeterminismDeterminism is the ability to analyze and predict, on arepeatable basis, the state of a process or function.Determinism can be achieved as a design goal or proventhrough exhaustive validation of a design.2.1.6 Degree of IntegrationThere are ma
46、ny technical and economic factors that affectthe degree of avionics integration. Integration istraditionally applied to reduce avionics weight andvolume. However, integration may be applied to reducethe number of data buses, types of data buses andassociated interfaces. This is particularly useful w
47、hen iteliminates the need for proprietary buses or unique buses.The concentration of data on an individual data bus mayincrease as a result of integration.COMMENTARYThe designer should exercise caution that integrationdoes not result in an unmanageable level ofcomplexity, contributing to excessive c
48、ertificationeffort and costly spares.2.1.7 Cost EffectivenessCost effectiveness should be viewed from the perspectiveof life-cycle costs and not viewed from the first cost.There is no advantage in optimizing first cost if the costof ownership is prohibitive.2.1.8 WeightWeight is a significant driver
49、 in developing avionicsequipment due to the recurring overhead cost (fuel cost)in carrying the avionics. The desire to minimize weightshould not affect avionics equipment performance,including reliability and maintainability.2.1.9 Application of Commercial-Off-The-Shelf (COTS)SoftwareUse of Commercial-Off-The-Shelf (COTS) softwareshould be considered as a means to reduce non-recurringdevelopment costs. However, the selection of a COTSsoftware supplier should be carefully considered in orderto be assured of long-term support, integrity andcertifiability.2.1.10 GrowthAirlines expect to hav
