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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
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 #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$e bit set: %&et read' accept data()
A
A
B Packet 1 Command Word from BC to RTA %) #/ transmit bit set: %Send data to RT %)()
B
B
C Packet 1 Status Word from RTA %): %.ere it comes,)
C
C
2
2 Packet 1 Status Word from RTA %0): %&ot it,)
2
+ + +
+ Packets - N +ata Words transmitted from RT %) to RT %0)
+ + + +
Note: Signals probed at RT input/output test plane
MIL-STD-1!B Avionics Bus. In'ormation Trans'er ExamplesMIL-STD-1!B Avionics Bus. In'ormation Trans'er Examples
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A(D)*A&I+% ,,A(D)*A&I+% ,,
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A(D)*A&I+% ,,. Main c#aractersiticsA(D)*A&I+% ,,. Main c#aractersitics
A-/ or A$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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A(D)*A&I+% ,,. Lin elementsA(D)*A&I+% ,,. Lin elements
"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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A(D)*A&I+% ,,. Lin elementsA(D)*A&I+% ,,. Lin elements
&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