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M5 > 5.4 Data buses > Flashcards

5.4 Data buses Flashcards

1
Q

data buses were designed and evolved to meet what requirements

A

efficient communication between their subsystems and components. must be as lightweight and reliable as possible, which means keeping wiring and connectors to a minimum

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2
Q

Avionics system designers used Analogue-to-Digital Converters (ADC) and Digital-to-Analogue Converters (DACs) .These require only two twisted pairs of wires to connect single data transmitters (sources) and single data receivers (sinks)

A

.

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3
Q

what is a single source and multiple -sink bus called

A

ARINC 429 (Aeronautical Radio Incorporated)

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4
Q

multiple-source with multiple-sinks buses

A

ARINC 629 and its military equivalent, MIL-STD-1553B.

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5
Q

time - division multiplexing

A

enables different forms of information to be transmitted through a single communication system.

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6
Q

when was ARINC founded

A

1929 in the United States

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7
Q

what data bus remains the standard for all aircraft

A

ARINC 429

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8
Q

ARINC 629 is how much faster than ARINC 429

A

20 times faster

data rate of 2 megabits per second

can handle 120 terminals instead of (ARINC429’s) 20

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9
Q

simplex means

A

the transmission can flow only in one direction, i.e., the communication is unidirectional. can only send data but not receive it vice versa

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10
Q

half duplex means

A

One transmitter, one receiver; the transmission can flow in both directions, but only one at a time (bi-directional with limitations)

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11
Q

full duplex means

A

One transmitter, one receiver; the transmission can flow in both directions at the same time (bi-directional)

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12
Q

the ARINC 429 specification describes the bus as an open loop transmission model

A

.

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13
Q

ARINC 429 is a

A

simplex bus with multiple receivers and can be thought of as a ‘shout’ or ‘broadcast’ bus

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14
Q

the transmitting LRU is known as the

A

source

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15
Q

each receiving LRU is called a

A

sink

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16
Q

ARINC 429 transmits sets of information at

A

periodic intervals

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17
Q

advantages of serial transmission

A

only a single line is required for transmission

only one set of digital circuitry is needed to process the data

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18
Q

ARINC 429 information is transmitted via a uni-directional bus, which is made up of

A

two 78 ohm twisted shielded wires

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19
Q

ARINC 429 defines two different transmission speeds:

A

Low-Speed (LS BUS) (12-14 kbit/s)
High-Speed (HS BUS) (100 kbit/s)

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20
Q

Low-speed and high-speed transmission can never occur on the same data bus. It is either a low-speed or high-speed bus.

A

.

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21
Q

Important data is transmitted often; less important data is transmitted less frequently. This is known as

A

information rate

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22
Q

BCD data (Binary Coded Decimal) is used for displays only, it is transmitted

A

twice per second on average

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23
Q

BNR (Binary) is processed by other LRUs and is therefore required to be transmitted 6 to 20 times a second.

A

.

24
Q

the use of SDI and SSM is not mandatory

A

.

25
Q

the label …

A

The Most Significant Bit (MSB) of the actual label is in the Least Significant Bit (LSB) of the ARINC 429 word and is transmitted first onto the bus; this causes the label to be transmitted onto the bus in reverse bit position order.

26
Q

the source/ destination identifier (SDI) function is used

A

When it is necessary to indicate the source of information

when the information is directed to a specific location (which has a minor function),

27
Q

The data bus cable is a pair of twisted wires which are not shielded.

A

.

28
Q

The ARINC 629 bus employs an inductive coupling technique used to connect the bus to receivers/transmitters

A

.

29
Q

Each LRU or Line Replaceable Module (LRM) is connected to its coupler by

A

a stub cable

30
Q

The stub cable contains two sets of

A

shielded twisted pairs of wires

31
Q

cabling arrangements of ARINC 629 data bus

A

data bus cable
LRU
current mode coupler
serial interface module
stub cable

32
Q

ARINC 629 system can be thought as a

A

party line

33
Q

ethernet terminology

medium =

A

Ethernet devices attach to a common medium that provides a path along which the electronic signals will travel

34
Q

ethernet terminology

segment =

A

Refers to a single shared medium as an ethernet segment. Segmentation is overcome by a bridge.

35
Q

node =

A

Devices that attach to that segment are stations or nodes.

36
Q

frame =

A

The nodes communicate in short messages called frames, which are variably sized chunks of information.

37
Q

jitter =

A

Is when the signal drifts from its reference position.

38
Q

frames =

A

The method that is used to stream data over ethernet systems.

39
Q

full duplex ethernet cable =

A

This allows data to be sent and received at the same time.

40
Q

CSMA/CD =

A

The acronym Carrier Sense Multiple Access with Collision Detection (CSMA/CD) describes how the Ethernet protocol regulates communication among nodes.

41
Q

collision detection

A

In Ethernet terminology, a collision occurs when they both spoke at once.

When stations detect a collision, they cease transmission, wait a random amount of time, and attempt to transmit when they again detect silence on the medium

42
Q

repeaters =

A

Repeaters connect multiple Ethernet segments, listening to each segment and repeating the signal heard on one segment onto every other segment connected to the repeater. By running multiple cables and joining them with repeaters, you can significantly increase your network diameter.

43
Q

the controller area network (CAN) bus is

A

a multi-master broadcast serial bus standard to connect electronic control units which is an advantage over ARINC 429.

CAN data bus is a serial communications protocol that supports distributed real-time control with a high level of security.

44
Q

the CAN bus was introduced when

A

1980s by Robert Bosch GmbH

45
Q

A CAN Bus operates at data rates of up to 1 Megabyte per second (Mbps) for cable lengths of less than 40 m.

if the cable length increases, what happens to the data rate

A

typically falls to 125 kilobytes per second (kb/sec) for 500 m (1640 ft) in length.

46
Q

The CAN Bus data frame consists of seven different bit fields:

A

Start of frame
Arbitration
Control
Data
CRC
ACK
End of frame

47
Q

A CAN base frame message begins with the start bit called

A

Start of Frame (SOF). It is a single dominant bit

48
Q

The arbitration field, which consists of the identifier and the Remote Transmission Request (RTR) bit,

A

is used to distinguish between the data frame and the data request frame called a “remote frame”.

49
Q

Cyclic Redundancy Check (CRC)

A

The integrity of the frame is guaranteed by the following CRC sum

50
Q

Advantages of the CAN Bus include:

A

No separate master bus controller

no need to retransmit the message; only the priority message is on the bus.

no need for any node to wait for the token (like a token ring network) to transmit the message.

With only the maximum capacity of the bus as a speed-limiting factor, the CAN Bus does not collapse or lock up.

51
Q

Error detection is done by:

A

Monitoring data transmitted on the bus. Every transmitter compares the bit level it transmitted with the bit level it received from the bus
Cyclic redundancy check
Message frame check
Bit stuffing

52
Q

Full duplex operation mode can only be used when:

A

The connecting medium is capable of simultaneous transmission and reception (full duplex).
The two computers communicating have a full duplex connection.
Both communicating computers are configured for full duplex connection.

53
Q

Full duplex systems have numerous advantages.

A

Data transfer is bi-directional
Data transfer is high speed (100 Mbit/s)
High data transfer rate
Virtual link concept
It involves one transmitter and multiple receivers

54
Q

ARINC 664

A

The Aircraft Data Communication Network (ADCN) systems communicate with each other using AFDX switches and full duplex quad cables.

55
Q

ARINC 664 (2)

A

For system redundancy, two networks are used: Network A and Network B. All systems are connected to both networks. Each system sends data to the receiving system via both networks. The receiver uses the first network to provide valid data

56
Q
A

M5 (12 decks)

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