Unit3 Avionics

8/4/2019 Unit3 Avionics

1/83

1

Unit 3, Digital Avionics

ArchitectureAvionics system architectureData

buses MILSTD 1553 BARINC429ARINC 629.


2/83

2

Syllabus

Avionics system architecture

Data buses

MILSTD 1553 BARINC 429

ARINC 629.


3/83

3

OSI Model

Data unit Layer Function

Hostlayers

Data 7. Application Network process to application

6. Presentation Data representation and encryption

5. Session Interhost communication

Segment 4. Transport End-to-end connections and reliability

Medialayers

Packet 3. Network Path determination and logical addressing

Frame 2. Data Link Physical addressing

Bit 1. Physical Media, signal
http://en.wikipedia.org/wiki/Logical_address


4/83

4

Pave Pillar Architecture

An Hypothetical Architecture for an highperformance Aircraft

Which has the following performance

requirement1. Paying attention to take off and landing on

flight controls

2. Having Two level maintenance & that has

MTBF=70 Hrs & MTTR=1.25 hr3.High percentage of Fault Detection & Fault

Isolation=99 & 98%


5/83

5

Major Avionic Architecture

Types, features and comparison


6/83

6

Scheme of General Avionic ControlSystem

ACS

Effector To DisplaysFor Pilot Alerting

SensorsACS-Avionic Control System

Inputs from Sensor1.Positional Data2.Environmental data3.Aircraaft State Data


7/83

7

Types

I. Federated Architecture= Dedicated& independent processing andcommunication system with no Data

Sharing eg. Arinc 429 and Saras of NAL

II. Integrated Modular Architecture- Areal time computer system with data

sharing between Sensors and Effectorsintegrated to flight control, landinggear, display control. - 1553 A/B eg.

Airbus & Arinc 629 (partially IMA & Fed)


8/83

8

Features -Federated

1. Stand-alone independent system withsensors, processing units and Effectors

2. No Data Sharing between sensors,

effectors and processing units3. Each system having own interfaces

(CPU, I/O) to sensors and actuators

(Effectors)4. Functions partitioned

Eg. ARINC 429


9/83

9

Federated Architecture Schematic


10/83

10

Components of FederatedArchitecture

User Interface for controlling the Effector

3 CPU-s each CPU for Sensor, Effectors,

5 I/O modules 4 Physical Communication Channel (1.User

Interface to Effector, 2. UI to Sensor,

3.Sensor to Effector and 4. a Feedbackfrom Sensor to UI)


11/83

11

Components of FederatedArchitecturecontd

1. User interface = landing gear,processing unit, display and control

2. Effector Used interface used forcontrolling the effector based uponfeedback collected from a sensor

3. Sensor

4. 3 Units connected by dedicatedcommunication channels.


12/83

12

Advantages of Federated Architecture

Each Function has its own fault tolerantcomputer and each box has a specificfunction, with specifically developed

hardware and software

Failure of one function has no effect onthe other system

Every system is a stand alone system


13/83

13

Disadvantages of FederatedArchitecture system

Developed from scratch, with the lack oftechnology re-use

Suffering from obsolescence issues for hardwarecomponents

Increased weight and power consumption

Hence increasing the weight of the aircraftresulting in poor fuel efficiency this introducesdedicated communication channels and also


14/83


15/83

15

Integrated Modular Architecture


16/83

16

Features of IMA

1. Sensor data shared between several systems2. In Core computer several modules identified

performing a specific function like the flight control,landing gear, display control, etc.

3. Multiple Federated application integrated into a singleplatform4. Strong Partitioning of Software & Two layer Software

Architecture5. Inter partitioning of Communication Facility & Client

Server inter partition Protocol6. Displaying of Status Messages7. Input/Output message handling by Message Handler

and System Executive


17/83

17

Advantages of IMA

Each Avionic Computer has Open SystemInterface called Application Program Interface

API with Plug and Play

Flexible communication having a logical channeland communication channel

Flexibility in Hardware Architecture

All LRM lightening protected,EMC and

environmentally protected Fault Tolerance in IMA

Full Duplex Switched Ethernet


18/83

18

Disdvantages of IMA

Specific function for each LRM ( autopilotmodule, flight management module notinterchangable)

Modules not field replacable

Multiple suppliers-not my problem


19/83

19

Air crtafts using IMA

1. F22 Raptor

2. Airbus 380 & Airbus A400

3. Boeing 7874. Sukhoi Super Jet 100


20/83

20

Two layer Software Architecture


21/83

21

Examples of IMA architecture

Airbus A350

Airbus A380

Boeing 787 Dassault Falcon 900


22/83

22

Comparison between IMA & Fed

1. Open Systemarchitecture with P&P

2. Fully Duplex

3.Only One CoreComputer

4. Field Replacable(LRM)except FM andAutopilot

5. Highly fuel efficient andlight weight

1. Closed Systemarchitecture with no P&P

2. Not Duplex

3. Many DistributedComputers

4. Not Field Replacable

5.Poor Fuel efficient andBulky.


23/83

23

Aeronautical Standards

ARINC, 1553 1773


24/83

24

Aeronautical Standards

ARINC-Aeronautical Radio Incorporated-Arinc 400 series and Arinc 600,700 and800 series, used by Boeing

MIL Military, MIL 1553 standard Airbus


25/83

25

ARINC 429


26/83

26

ARINC 429 in brief

An Old, Simplex, Dedicated I/O Opensystem

Point to Multipoint, Asynchronous system

Operate on both discrete and analogsignals

Sub Systems include FMS,ILS, VHF,Displaysystem


27/83

27

ARINC-429

Unidirectional Bus operating at either 12.514.5 kbps or 100 kbps

A Simplex Bus ( one TX and manyReceivers)

No Bus Controller, RT, or Bus Monitorcontrary to 1553

ARINC use 32 Bit word with Odd Parity

Waveform for ARINC is RTZ Bipolar


28/83

28

RTZ Bipolar Format


29/83

29

ARINC Avionic Data Bus in Boeing


30/83

30

Features of ARINC 429

A standard that communicates betweenavionics equipment and systemsconnected with Twisted Pair wires

Employs a Unidirectional Data BusStandard called Mark 33 DigitalInformation system

Data speed =12.5 or 100 kbps Transmission and reception on separate

ports so that many wires required


31/83

31

ARINC 429 Architecture


32/83

32

ARINC 429 INTERFACE thru RS232


33/83

33

Word Format for Arinc 429

32 bit word by two wire transmissioncontaining 5 fields

Protocol= Point to Multi- Point Protocol

Has both low speed and high speed

Parity Bit = MSB

Five fields ; 2 for numerical data, 1 fordiscrete data, 2 for alphanumeric data

Data = BCD


34/83

34

Arinc Word Format

32 BIT Format

1-8 for Label (type of Data-BCD)

9 & 10 for SDI ( Source DestinationIdentifier)-1 TX and 20 RX

11 to 29 Data

30 & 31 for SSM( Sign/Status Matrix) 32 for Parity


35/83

35

Word Format for Arinc 429

3230 3181 9 10

0-32 bits for Arinc 4291-8 bit for Label

Bit 9 & 10 Station Identifier11-29 for Data

30 & 31 bit =Sign and Status BitBit 32 for Parity


36/83

36

Arinc 429 Word Format


37/83

37

Other ARINC Protocols

1. Arinc 419

2. Arinc 453 in Inertial Navigation system

3. Arinc 568 in Flight Recorder4. Arinc 619

5. Arinc 629 used in Boeing 777


38/83

38

ARINC 629

General Features,Protocol Layer,TimingDiagram (Periodic and Aperiodic)

Comparison between 429 & 629


39/83

39

General Features of ARINC 629

1. ARINC629- Multi transmitter to Multi receivers

2. ARINC 629 = two independent MAC protocolsfor communications across a 20 Mbps Serialdata bus

3. High Speed Bi directional Bus (used in latestBoeing 777)

4. ARINC 629- periodic and a-periodictransmissions

5.2 Protocols-Basic Protocol and Combinedprotocol;

6. Basic protocol for flight controls,

7. Combined protocol for flight managementsystem

8. No bus Controller required


40/83

40

4 Protocol Layers of 629


41/83

41

4 Protocol layers of Arinc 629

1.Physical layer- Layer-Main computational componentinteracting with shared memory, using 2 Mbps SerialData Transmission on Twister pair cable-

Multiple timers and circuitry employed for collisionavoidance on twisted pair cable with 20 Mbps serial

data 2.Data Link Layer-dealing with single source to many

terminals for data Using TDMA Has Basic Protocol and Combined protocol existing

individually in the same bus due to their differences. Using Collision Avoidance logic, for accessing a

channel across all terminals 3. Network Layer-dealing with networks for 20 bit

words upto 256 data words 4.Upper Layer-presenting application, session,

presentation and transport layer

l ( f l h


42/83

42

Basic Protocol-BP ( for Flightcontrol)

CSMA/CA scheme defined in BP

Operate either on periodic or aperidic, butnot simultaneously

Variable 31 Word Strings

Used in Flight control long messagesdriving the bus from periodic to aperiodicmode


43/83

43

Protocol Layer-contd

Basic Protocol (DL):All transmissions fixedfor periodic mode and individualtransmissions vary for a-periodic mode-

have Terminal Gap, Synchronization gap


44/83

44

Combined Protocol-CP ( FMS system)

CAMA/CA defined in CP

Shortfalls in BP for Periodic and Sporadicdata transmissions.

Sporadic data serviced when all periodicdata have been completed

Unique TG pre-assigned

Periodic Data compressed into Burst,separated by TG


45/83

45

Difference between BP & CP

BP CP

Transmitting either

Periodic or aperiodic

Transmitting both

periodic and aperiodicTerminals transmit atconst speed, if there isno overload

Terminals transmit atperiodic mode even ifthere is overload

If there is overload,data switched to a-periodic mode

Terminals given equalopportunity to switchfor overload


46/83

46

ARINC 629 card


47/83

47

Arinc 629 Interface


48/83

48

Word Format for ARINC 629

20 bit word using CSMA/CA protocol

11 bits as Label

1 Bit for Parity 4 bits for CID

4 Bits for Synchronization(High Low

Synchronization)


49/83

49

Word Format in Arinc 629

11911

12 15

11 to 1 Labels (numberedin reverse)

0

0 for Parity 12-15 for ChannelIdentification CID

16

16-19-4 bits for sync


50/83

50

Channel Identification CID

629 messages -series of word strings

Label- the First word in a string (11-1)marked in reverse

Channel identification-the word stringafter a Label (12-15)

CID-to identify a unit in a word string


51/83

51

Label Word

16 Bits assigned between Synchronizationbits and parity bit- are Labels

Synchronization bits to identify a Label

Word

Label bits numbered in reverse

3 Ti i C diti f ARINC 629


52/83

52

3 Timing Conditions of ARINC 629to access a terminal

1. Transit timing condition T1- themoment the terminal starts transmitting-T1 starts

2. Synchronization gap-SG conditionSG-starts the moment the terminal isquiet

3. Terminal Gap condition TG-anunique timer assigned to the terminal;TG begins when SG is elapsed. TG & SGcannot overlap


53/83

53

Timing diagram-Periodic mode

Constant T1

TnT2T1

Delay until T1 elapse

TG2 SG


54/83

54

Timing diagram-Periodic mode

When terminal starts Transmission, T1timer starts

SG timer starts when the Bus is quiet

TG timer starts when SG has elapsed


55/83

55

Timing Diagram-Aperiodic Mode

Variable T1

startstopT1 T2

Tn

SG

TG1 TG2TGn


56/83

56

Comparison between 429 & 629

No

Parameter ARINC429

ARINC629

1 Architecture On Federated On IMA

2 Flow of Data Unidirectional

Simplex

Bi DirectionalDuplex

3 Word Size 32 bit in RTZ 20 bit word

4 Protocol SP-MP

Asynch.

Basic &Combined

MP-MP

Sync & Async

5 Transmission Speed 12.5 Kbps or

100 kbps

2 Mbps Serial


57/83

57

1553 B


58/83

58

1553 B Salient Features

A Serial TDMA 1 Mbps Data Bus commonly usedin Civil Aircrafts, ships, submarines

Using both Twisted Pair and Transformer forcoupling

3 Devices ( BC,RT & BM) to the bus, RT-standalone Unit

A dual redundant Balanced physical layer,Differential Network Interface, TDM, Half-duplex

command/response protocol witho 31 remoteterminals


59/83

59

1553 A & 1553 B

1553 AMIL std, not fully defined fromthe user point

1553 Bfully defined from the user point

of view for both hardware and software-two types of Coupling (STP andTransformer) to the data bus


60/83

60

1553 Block diagram


61/83

61

1553 B in an Aircraft


62/83

62

1553 Architecture


63/83

63

1553 Bus Structure


64/83

64

1) Bus controller- the Master Device responsiblefor directing the flow of data into the bus

2) Remote Terminal-responsible for receiving

the data and storing the data for flight test,maintenance and mission analysis

3) Bus Monitor-Responding to the commandsaddressed to Bus Monitor where 31 RT-s

connected, but cannot transmit data

Architecture of 1553 B


65/83

65

Architecture of 1553 B

RemoteTerminal 1

RemoteTerminal 2

RemoteTerminal 3

Bus Monitor

Channel A

Channel B

BUSCO

N

Data Encoding in 1553 B-


66/83

66

Data Encoding in 1553 B-Manchestor


67/83

67

Industry MIL Standard 1553 B


68/83

68

Components of 1553 B

A dual-redundant MIL-STD-1553B busA Bus Controller responsible for initiating

message communication over the bus, detectingand correcting errors

Three Remote TerminalsResponsible foracquiring data from one Subsystem andtransferring to another subsystem(eg, data frominertial navigation to cockpit display)

A Bus Monitor-Responsible for monitoring alltransactions over the bus and storing the datafor later analysis, but does not transmit


69/83

69

Technical Features of 1553 B

Data Speed 1 Mbps

Data Encoding by Manchestor

Modulation of data by PCM

Access by TDMA

Data Size=16 bit word

3 types of data transfers between RT andBC


70/83

70

Types of Data Transfer in 1553 B

Bus Controller to Remote Terminal- BC toRT

Remote Terminal to Bus Controller-RT to

BC

Remote Terminal to Remote Terminal- RTto RT


71/83

71


72/83

72

1553 B Bus Controller Summary

Supporting 128 kBytes memory

Synchronous or Asynchronous interface

Clock rate 12, 14, 16 or 24 MHz

Verilog Source Code

Use Ma nchestor Encoding


73/83

73

Components of 1553B

1. Encoder/Decodeer-input serial data usingManchestor coding with 12,16 or 24 Mhzclock

2. Protocol Controller for messagesequencing and error control

3. CPU access the Block controller withinthe system

4. Backend interface enabling theconnection to a memory device

Simple Remote Terminal ( Redundant


74/83

74

Simple Remote Terminal ( RedundantBus)


75/83

75

Word Format of 1553B

3 Types of Words in 1553 B of 20 bitswith 3 bits for synchronization, 16 bitsdata and 1 bit for parity

1. Command Word CW transmitted by BC

2. Status Words SW transmitted by RT

3. Data Word DW transmitted by BC or RT


76/83

76

1553 B Bus Word Format


77/83

77

Status Word=20 bits(Tx by BC)

Transmitted by RT from BC

3 bit-time sync pattern (same as for acommand word)

16 bits for Data in Status

1 parity check bit.


78/83

78

Status Word=20 bits

1163

One word=20 Bits

Sync Data Parity

d d ( b )


79/83

79

Command Word ( Tx by BC)

20 bit word Transmitted by Bus Controller ofwhich (no BC address)

3 bits for sync using Manchestor coding 5 bits for address of RT

1bit Transmit/Receive (T/R) indicating datadirection (T means Data recd by RT)

5 bits for sub address under RT address tomemory etc

5 bit for data word count,indicating the wordcount after the sub address. 1 bit for parity check (using Odd parity)

Command Word ( Transmitted by


80/83

80

Command Word ( Transmitted byBC)

One Command word=20 Bits

35 1 5 5 1

Sync RT Address T/R Sub address Word Count Parity

D W d (b RT/BC)


81/83

81

Data Word (by RT/BC)

20 bit Data Word transmitted by RT or BCagainst a BC request

3 bits for sync pattern (opposite in

polarity from command and status words)

16 bit for data field

1 bit for parity check bit.

D t W d ( T b RT/BC)


82/83

82

Data Word ( Tx by RT/BC)

3 16 1

Sync Data Parity

Di ti ti b t 629 & 1553


83/83

Distinction between 629 & 1553No Description 629 1553

1 Architecture IMA IMA

2 Word Format in Sync &

Parity

RTZ

Odd

Manchestor

Odd

3 Terminals on Data Bus 2(RT & BM) 3 (RT,BC,BM)

4 Coupling by STP STP&Transformer

5 Data System & speed Multiplex

2 Mbps

Multiplex

1 Mbps

6 Data Word Size 20 Bit 16 bit

Documents

Unit3 Avionics