ARINC629

Question 1

What is the maximum amount of Rx/Tx the 629 bus will allow?

Answer 1

120 Tx/Rx

Question 2

What type of serial data bus is the ARINC629?

Answer 2

Bi-directional/Duplex

Question 3

What type of wires can the ARINC629 be and how long are they?

Answer 3

Can be 100m twister copper

Unlimited length fiber optic

Question 4

What is the speed of the ARINC629?

Answer 4

2MB/s

Question 5

What is the improvement of ARINC629 from 429?

Answer 5

Less weight and high speeds

Question 6

Can you transmit on more than one LRU at a time for the ARINC629?

Answer 6

No, can transmit only one at a time

Question 7

How many bus control units does the ARINC629 have?

Answer 7

It does not have any bus control units

Question 8

How many data busses do you need for 2 way communications?

Answer 8

Only one data bus for 2 way communication

Question 9

What type of coupling does the ARINC629 use and what are its advantages?

Answer 9

No physical interruption
less loose connections
improved reliability

Question 10

What is the initial data produced by the LRU and in what format?

Answer 10

A digital signal in the Manchester format

Question 11

When the doublet changes from a binary 1 to 0 and vice versa, what does it produce?

Answer 11

It produces a short pulse(bumps)

Question 12

How does the clock pulse react on the 629 and what is its purpose?

Answer 12

Becomes opposite of the current binary high/low and is for synching

Question 13

Why is the Receiver voltage lower than the transmit voltage?

Answer 13

For system losses

Question 14

What are the benefits of using fiber optic cable?

Answer 14

immune to EMI and lighting transients

Question 15

What is the copper wire impedance?

Answer 15

130ohms

Question 16

What is the purpose of the timing signal in each bit?

Answer 16

Self clocking

Question 17

How long is each bit?

Answer 17

100uS

Question 18

This component moves data to and from the LRU memory, what is it?

Answer 18

Terminal Controller

Question 19

What is the purpose of the serial interface module?

Answer 19

• Connects TC to data bus STUB
• Changes Manchester current to analog voltage doublet
• informs TC of system failure

Question 20

How many wires/cables does the stub have?

Answer 20

4 (2Rx, 2Tx)

Question 21

What is the max length of the stub?

Answer 21

75ft

Question 22

What is the purpose of the stub cable?

Answer 22

Connects TC to CMC

Question 23

What is the CMC and what is its purpose?

Answer 23

It is the current mode coupler and its to get the LRU to the 629 bus using a transformer coupler

Question 24

How many inductive couplers in one unit and what is the purpose?

Answer 24

2 inductive couplers in one unit

one for redundancy

Question 25

In transmit, the CMC does what?

Answer 25

Changes v doublet to current doublet

Question 26

Current doublet to V doublet is changed where?

Answer 26

Receiver CMC

Question 27

Each message has what?

Answer 27

31 word strings | 4bit sync gap ident

Question 28

How many data words in 1 word string?

Answer 28

256 data words | starts with label then data words

Question 29

The Label word has how many bits and what are they?

Answer 29

20bits - 12 label - 1 parity - 4 label extension - 3 sync pulse

Question 30

The Data word has how many bits and what are they?

Answer 30

20 bits - 16 data - 1 parity - 3 sync

Question 31

What is the purpose of the PPSSP and PSSP?

Answer 31

Syncing at beginning of each word

Question 32

The 629 bus is also referred to as?

Answer 32

Periodic, Aperiodic multi-tx bus

Question 33

What are the 3 timing signals used to sequence the transmission of the 629?

Answer 33

Terminal Gap Synch Gap Transmit Interval

Question 34

Which is longer than the longest TG?

Answer 34

Synch Gap

Question 35

What is the purpose of the TG?

Answer 35

determines the priority of transmission for LRUs

Question 36

What does a short TG mean?

Answer 36

High priority

Question 37

What is the purpose of the Synch Gap?

Answer 37

acts as a reset signal | - LRU can only tx once until next SG

Question 38

What is the purpose of the TI?

Answer 38

prevents any one user from dominating the bus

Question 39

What is a periodic bus?

Answer 39

All tx completed within TI completion

Question 40

If the TI is exceeded due to an LRU tx longer than average message, what is the mode now?

Answer 40

Aperiodic

Question 41

What does an impedance change signify?

Answer 41

A faulty bus

Question 42

If you pass the ohmeter test but still fail to transmit the signal what is the issue?

Answer 42

High impedance

Question 43

What are the 3 ways transmission of digital data can be affected by the data bus system?

Answer 43

Drop Outs Attenuation Interference

Question 44

When a portion or portions of the signal are lost during tx what is it being affected by?

Answer 44

Drop Outs

Question 45

What is Drop Outs caused by?

Answer 45

Loose Connections | Intermittent Signals

Question 46

What does attenuation do?

Answer 46

makes signal weak or tx V too low that receiver does not recognize

Question 47

How does attenuation happen?

Answer 47

Loss of power due to resistance, dbm, db

Question 48

How do you solve attenuation?

Answer 48

LRU isolation | LRU inductive coupling

Question 49

What is it called when unwanted signals are induced into the bus?

Answer 49

Interference

Question 50

What causes interference?

Answer 50

Improper shielding | Leaks