AET Data Bus Systems and Protocols 1 — Questions and Answers
Question 1: What is the data transfer rate of ARINC 429 operating in high-speed mode?
- 12.5 kbps
- 100 kbps (Correct answer)
- 1 Mbps
- 10 Mbps
Correct answer: 100 kbps
ARINC 429 high-speed mode operates at 100 kbps, while its low-speed mode operates at 12.5 kbps.
Question 2: Which data flow topology best describes ARINC 429?
- Bidirectional multi-transmitter bus
- Unidirectional point-to-multipoint bus (Correct answer)
- Bidirectional command/response protocol
- Full-duplex ring topology
Correct answer: Unidirectional point-to-multipoint bus
ARINC 429 is a unidirectional bus where a single transmitter sends data to up to 20 receivers simultaneously.
Question 3: How many bits are contained in a standard ARINC 429 data word?
- 16 bits
- 24 bits
- 32 bits (Correct answer)
- 64 bits
Correct answer: 32 bits
An ARINC 429 data word is 32 bits long, consisting of an 8-bit label, SDI, data field, SSM, and a parity bit.
Question 4: What does the 8-bit 'label' field in an ARINC 429 word identify?
- The destination receiver address
- The type or parameter of data being transmitted (Correct answer)
- The identity of the source transmitter
- The error correction code appended to the word
Correct answer: The type or parameter of data being transmitted
The 8-bit label field identifies the type of data or avionics parameter (e.g., airspeed, altitude) contained in that word.
Question 5: Which encoding scheme is used by ARINC 429?
- Non-Return to Zero (NRZ)
- Manchester II Biphase
- Bipolar Return to Zero (BPRZ) (Correct answer)
- 4B/5B encoding
Correct answer: Bipolar Return to Zero (BPRZ)
ARINC 429 uses Bipolar Return to Zero (BPRZ) encoding with three voltage states: HIGH (+10 V), NULL (0 V), and LOW (−10 V).
Question 6: What is the maximum number of receivers that can be connected to a single ARINC 429 transmitter?
- 5
- 10
- 20 (Correct answer)
- 50
Correct answer: 20
A single ARINC 429 transmitter can drive up to 20 receivers on one unidirectional bus.
Question 7: What information does the SSM (Sign/Status Matrix) field provide in an ARINC 429 word?
- Signal synchronization timing
- Data sign and equipment operational status (Correct answer)
- Secondary system monitor readings
- Serial signal modulation type
Correct answer: Data sign and equipment operational status
The SSM field provides the sign of the numeric data and indicates the operational status (e.g., normal, failure warning) of the transmitting equipment.
AET Data Bus Systems and Protocols 1
What is the data transfer rate of ARINC 429 operating in high-speed mode?