Introduction to Avionics Buses v2

7/21/2019 Introduction to Avionics Buses v2

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Introduction to Avionics BusesIntroduction to Avionics Buses


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Introduction to Avionics BusesIntroduction to Avionics Buses

Avionics Buses come up with the massive introduction of digital technology in aviation

electronics.

The introduction of a bus or data transmission medium (wires or optical fiber) improves the

interconnection of the previous system, reduced weight and made maintenance easier.

Sharing the use of this medium various subsystems can communicate each other, one at a

time and in a defined sequence.

odern Avionics Buses are very similar to !ocal Area "etwor#s (!A") or even use some

elements of commercial networ#s.


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Introduction to Avionics Buses. Example Boeing B777Introduction to Avionics Buses. Exam

ple Boeing B777

The plane primary control surfaces and its sign conventions are shown below$

%.&udder. 't is intended to produce aw control.

.*levator. They are intended to produce +itch control.

.Ailerons. They are intended to produce &oll control.


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Introduction to Avionics BusesIntroduction to Avionics BusesThe figure below shows some of the Avionics Buses used in aircrafts. The most used Buses

are$

Avionics Buses are normally &edundant

and guarantee deterministic timing in

the data transfers


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MIL-STD-1!B Avionics BusMIL-STD-1!B Avionics Bus


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MIL-STD-1!B Avionics Bus. "#$sical elementsMIL-STD-1!B Avionics Bus. "#

$sical elements


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MIL-STD-1!B Avionics Bus. Transmission MediaMIL-STD-1!B Avionics Bus. Transmission Media


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MIL-STD-1!B Avionics Bus. Bus %ontrollerMIL-STD-1!B Avionics Bus. Bus %ontroller

Bus %ontroller

Bus Monitor


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MIL-STD-1!B Avionics Bus. &emote TerminalMIL-STD-1!B Avionics Bus. &emote Terminal


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MIL-STD-1!B Avionics Bus. In'ormation Trans'er (ormatMIL-STD-1!B Avionics Bus. In'ormation Trans'er (ormat


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%%

Example #1: BC to RT Transfers (BC sends data to RT)

Note: Signals probed at BC input/output test plane

A Packet - Command Word from BC to RTA !" #/ recei$e bit set: %&et read' accept data()

A

A

B Packets - * +ata Words transmitted from BC to RT

B B B B B

B B B

C Packet - Status Word from RTA !": %&ot it,)

C

C

MIL-STD-1!B Avionics Bus. In'ormation Trans'er ExamplesMIL-STD-1!B Avionics Bus. In'ormation Trans'er Examples


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%

Example #2: RT to BC Transfers (BC requests data from RT)

Note: Signals probed at RT input/output test plane

A Packet - Command Word from BC to RTA ! #/ transmit bit set: %Send me data()

A

A

B Packet - Status Word from RTA !: %.ere it comes,)

B

B

C Packets - +ata Words transmitted from RT to BC

C C C C

C C C



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%

Example #3: RT to RT Transfers (BC requests RT 2 to send data to RT 1)

Scope #a$eforms not a$ailable

A Packet - Command Word from BC to RTA %0) #/ recei$e bit set: %&et read' accept data()

A

A

B Packet 1 Command Word from BC to RTA %) #/ transmit bit set: %Send data to RT %)()

B

B

C Packet 1 Status Word from RTA %): %.ere it comes,)

C

C

2

2 Packet 1 Status Word from RTA %0): %&ot it,)

2

+ + +

+ Packets - N +ata Words transmitted from RT %) to RT %0)

+ + + +

Note: Signals probed at RT input/output test plane



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A(D)*A&I+% ,,A(D)*A&I+% ,,


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A(D)*A&I+% ,,. Main c#aractersiticsA(D)*A&I+% ,,. Main c#aractersitics

A-/ or A$ionics "ull +uple3 S#itc4ed 2t4ernet is one of the most advanced Avionics

Buses. 't has been implemented in the Airbus A01

'ts main characteristics are$

+eterministic Timing means that the networ# guarantees that data will arrive to destination

with a given frequency (or bandwidth) and latency (delay).


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A(D)*A&I+% ,,. "#$sical elementsA(D)*A&I+% ,,. "#$sical elements

The topolog' of the A-/ networ# is shown below$


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A(D)*A&I+% ,,. Lin elementsA(D)*A&I+% ,,. Lin elements

2ne of the main characteristics of A-/ is that *S connect each other trough 3irtual !in#s

(a logical unidirectional channel).


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"rames( 'n *thernet data is transferred in data pac#ets called frame. This data pac#ets can

contain up to %411 bytes of data (payload).

'n A"+5, there are two parameters that define the bandwidth (bits per second) of each 67$

0( 7ma3defines the number of bytes of each frame up to its ma5imum possiblevalue

( BA&defines the number of frames per second (this parameter define the latency

and since it is ensured by the networ# ma#ing the communication deterministic)

6ow many bps are allocated to a 3! with !ma57%11 and BA879:;


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&edundancy is obtained by using of two networ#s


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A(D)*A&I+% ,,. Anal$sing +et/orA(D)*A&I+% ,,. Anal$sing +et/or

Structure of the 'nternet Suite +rotocol.


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A(D)*A&I+% ,,. Air0us A!2A(D)*A&I+% ,,. Air0us A!2

A-/ in the Airbus A01


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A(D)*A&I+% ,,. Air0us A!2A(D)*A&I+% ,,. Air0us A!2

A-/ in the Airbus A01


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Avionics electronics andAvionics electronics and

pacagingpacaging


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Avionics electronics and pacaging. MicroelectronicsAvionics electronics and pacaging. Microelectronics

Traditionally, the electronics parts are tested (screened) under certain environmental

conditions, mainly temperature, and are classified in three ranges in grade of severity$

%.


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Avionics electronics and pacaging. L&3Avionics electronics and pacaging. L&3

Traditionally, Avionics electronics are pac#aged in modules called !&? or !ine

&eplaceable ?nits, li#e the one shown below

A s'nc4rois a type of rotary electrical transformer that is used for measuring the angle of a rotating machine


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Avionics electronics and pacaging. Environmental conditionsAvionics electronics andpacaging. Environmental conditions

All the Avionics modules are produced and tested to withstand harsh environmental

conditions

A i i l i d

i E i l di i


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Avionics electronics and pacaging. Environmental conditionsAvionics electronics andpacaging. Environmental conditions

A i i l i d i EMI " iA i i l t i d

i EMI " t ti


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Avionics electronics and pacaging. EMI "rotectionAvionics electronics and pacaging. EMI "rotection*lectro@agnetic 'nterference (*') protection using -araday


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Avionics electronics and pacaging. "acaging StandardsAvionics electronics and pacaging. "acaging Standards

A i i l t i d i IMAA i i l t i d

i IMA


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Avionics electronics and pacaging. IMAAvionics electronics and pacaging. IMA

Introduction to Avionics Buses v2

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