The document discusses several avionics data buses used for digital communication within aircraft systems. It describes the evolution from early single-source single-sink configurations to modern multi-source multi-sink buses. Key buses covered include ARINC 429, ARINC 629, MIL-STD 1553, and MIL-STD 1773. ARINC 429 uses a single-source multi-sink topology with transmission rates from 12-100kbps. MIL-STD 1553 is a half-duplex multi-source multi-sink bus that operates at 1Mbps and coordinates data transfer through a central Bus Controller. MIL-STD 1773 is similar to 1553 but uses optical cabling instead of voltage-based

1. AVIONICS BUSES
Presented By:
YASIR MUNIR
HAZIQ AMJAD
COLLEGE OF AERONAUTICAL ENGG.
AVIONICS ENGINEERING DEPTT.
yasir2761@gmail.com
haziqamjad51@gmail.com

2. TABLE OF CONTENTS
INTRODUCTION
• BUS
• EVOLUTION OF BUSES
• TYPES OF TRANSMISSION
TYPES OF AVIONIC BUSES
• ARINC 429
• ARINC 629
• MIL-STD 1553
• MIL-STD-1773
2

3. BUSES
What is a BUS?
In computer architecture, a bus is a communication
system that transfers data between components inside a
computer, or between computers.
 The specification for data transmission is drawn by
Aeronautical Radio, Incorporated (ARINC).

4. EVOLUTION OF AVIONICS BUSES

5. COMMON TYPES OF SERIAL DIGITAL DATA
TRANSMISSION ARE:
Single source-single sink
Single source-multiple sink
Multiple source-multiple sink.

6. SINGLE SOURCE-SINGLE SINK
 Earliest application
 Comprises a dedicated link from one piece of equipment
to another
 Developed in the 1970s for use on Tornado and Sea
Harrier avionics systems

7. SINGLE SOURCE-MULTIPLE SINK
 One transmitting source transmits data to a number of
recipient pieces of equipment (sinks)
 ARINC 429 is an example of this data bus which is
widely used by civil transport and business jets.

8. MULTIPLE SOURCE-MULTIPLE SINK
Multiple transmitting sources transmits data to multiple
receivers.
This is known as a full-duplex system and is widely
employed by military users
(MIL-STD-1553B) and by the B777 (ARINC 629).

9. MAJOR DIGITAL DATA BUSES
 ARINC 429
 ARINC 629
 MIL STD 1553

10. ARINC-429
10

11. ARINC-429
Topology
Bit rates
Encoding
Word Format
Data Format

12. TOPOLOGY
&
BIT RATE
 Single source multiple sink
 Limitation of input impedance on no. of receivers
 Maximum up to 20 receivers
Two ranges of transmission rates are defined
High Speed at 100 kbps ±1%
Low Speed in the range 12 to 14.5 kbps

13. BUSTOPOLOGY

14. STARTOPOLOGY

15. ENCODING
The signal has three states 'HI', 'NULL' and 'LOW'
represented by the differential voltage between the two
wires of the cable.
A logical ‘1’ is signaled by transmission of a +10 ±1V
pulse followed by a 0±0.5V null period.
A logical ‘0’ is signaled by transmission of a –10 ±1V
pulse also followed by a 0 ±0.5V null period.

16. WORD FORMAT
 Organizes data in 32 bit words
Typical word consisting of five parts:
 Label
 Source/Destination Identifier (SDI)
 Data field
 Sign/Status Matrix (SSM)
 Parity bit

17. DATA
 Two’s complement binary data
 BCD (2/10) data
 Discrete bits
 Maintenance data
 Special Alphabet (Symbol and numeric)
17

18. LABEL
 Encoded in octal
 Each sink is required to inspect the Label field to
represent the type of information
 Each data item is assigned a label code and each
source may have up to 255 Labels
18

19. SOURCE/ DESTINATION
IDENTIFIER (SDI)
 Contains just two bits
 Main functions are to:
 indicate the intended destination on a multi-sink bus
 identify the source on a multi-source bus
 add an extension to Label

20. SIGN/STATUS MATRIX (SSM)
&
PARITY
 Indicate sign information
 Unique implementation of the SSM Sign function
 Indicate the source equipment status
 Imposes odd parity on the word
 If even – mistake!!!

21. ARINC 429

22. ARINC-629
22

23. HISTORY
Relatively new and not widely used
Boeing Commercial Airplane Group (BCAG)
 Digital Autonomous Terminal Access Communication
(DATAC) protocol
 Recognized as an air transport standard by ARINC in
spec 629
Boeing 777

24. ARINC 629
 Source transmits either broadcast or address specific
message to all or specific receiver or sinks
 If the sinks equipment needs to reply, each will need to
be fitted with own transmitter and a specific physical bus
24

25. BUS TOPOLOGY
25

26. ARINC-629
Multi-transmitter Data Bus
Serial data bus with distributed media access
Bit rate
Encoding
Message length
Number of nodes

27. BIT RATE
&
ENCODING
 2 Mbps
 Bipolar Manchester doublets
27

28. WORD FORMAT
A message has variable length and is comprised of up to
31 word strings
Each word string has variable length and contains
 one (20 bit) label word
 up to 256 (20 bit) data words

29. MESSAGE STRUCTURE
29
Message
Max 31 word string /
gap 4 bits
Each label
20bits/label-12/ext-4/3 sync/1
parity
Each data word
20bits/ 16 data/ 3 sync/ 1
parity
Each word string
Label + 256 data words

30. ARINC-429 VS ARINC-629
30

31. ARINC-429 VS ARINC-629
31

32. ARINC-429 VS ARINC-629
32

33. MIL-STD-1553
33

34. HISTORY
 Developed at Wright Patterson Air Force Base since
1970s
 Published First Version 1553A in 1975
 Introduced in service on F-15 Program
 Published Second version 1553B in 1978

35. OVERVIEW
35

36. 1553A vs 1553B
36

37. Data Rate
Message Length
Data Bits per Word
Transmission Technique
Encoding
Protocol
1 Mbps
32 Word Strings(maximum)
16 Bits
Half - Duplex
Manchester II Bi-phase
Transmission Mode
Word Length 20 Bits
Voltage Mode
Command Response
Operation Asynchronous
SPECIFICATIONS OVERVIEW

38.  BUS CONTROLLER (BC)
 REMOTE TERMINAL (RT)
 BUS MONITOR (BM)
 TRANSMISSION MEDIA
ELEMENTS

39. BUS CONTROLLER
Main function is to provide data flow control for all
transmissions on the bus.
It must transmit , receive and coordinate the transfer of
information on the data bus.
All information is communicated in command/response
mode - the BC sends a command to the RTs, which
replies with a response.
39

40. REMOTE TERMINAL
Device designed to interface various subsystems with the
1553 data bus.
May be embedded within the subsystem itself, or be an
external interface to tie a non-1553 compatible device to
the bus.
40

41. BUS MONITOR
Listens to all messages on the bus and records selected
activities
A passive device that collects data for real-time or post
capture analysis
Store all or portions of traffic on the bus, including
electrical and protocol errors
BMs are primarily used for instrumentation and data bus
testing
41

42. TRANSMISSION MEDIA

43. BUS ARCHITECTURE

44. TRANSMISSION METHOD
Modulation
The signal shall be transferred over the data bus in
serial digital pulse code modulation form.
Data Code
Manchester II bi-phase level.
A logic one shall be transmitted as a
 bipolar coded signal 1/0 (i.e., a positive pulse followed by a
negative pulse). A logic zero
 shall be a bipolar coded signal 0/1 (i.e., a negative pulse followed
by a positive pulse).
 A transition through zero occurs at the midpoint of each bit time
(see Figure 3-2).
44

45. 45

46.  COMMAND WORD
 DATA WORD
 STATUS WORD
WORD FORMAT

47. 19181716151413121110987654321 20
COMMAND WORD
SYNC
TERMINAL
ADDRESS
T
R
SUBADDRESS
OR MODE
WORD COUNT
MODE CODE
PARITY

48. 19181716151413121110987654321 20
PARITY16 BIT DATASYNC
DATA WORD

49. 19181716151413121110987654321 20
TERMINAL
ADDRESSSYNC
MessageError
Instrumentation
ServiceRequest
Reserved
Busy
STATUS WORD
TERMINAL
ADDRESSSYNC
MessageError
Instrumentation
ServiceRequest
Reserved
Busy

50. MIL-STD-1773

51. Optical cabling
Identical Data encoding and word formats
Exception
–Pulses are defined as transitions b/w 0 (off) and 1
(on)
–Not b/w + and - voltage transitions since light cannot
have a negative value
MIL-STD-1773

52. THANK YOU
52

53. QUESTIONS?
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