5.4 Data Buses NEW Flashcards
Wiring utilized to transmit data caries only a negligible current, just sufficient to do what?
Switch a transistor ON or OFF or to carry an audio signal which is then amplified at its destination.
What voltage levels are required for Binary 0?
0 to 0.8V
What voltage levels are required for Binary 1?
2 to 5 Volts
What are the 2 ways of data transfer between systems?
Parallel data transfer and Serial data transfer.
In serial transfer the data is transferred over?
The same line in sequence.
What triggers the transfer of data?
Clock pulses
What is the typical method of speeding up s serial data bus?
Multiplexing
In parallel transfer each bit is taken from?
A separate circuit and is transmitted over a separate line.
What are the advantages of parallel transfer and Disadvantages.
Much faster. Disadvantage = much more hardware, more space and weight.
What are the benefits of multiplexing?
Significant reduction in weight of wires and improved circuit reliability.
How does multiplexing operate?
Via synchronized rotating contacts connecting matching input and output lines in sequence. Data transmitted over the common transmission line.
In reality multiplexing is usually achieved by?
Logic gates responding in sequence to clock pulse signals.
What is the purpose of the shielding on the twisted wire pair?
Spike protection, eliminates EMF, guarantee’s accurate transmissions
What is the purpose of the twisted wire?
Magnetic fields induced by the currents flowing through them will cancel each out out, eliminating EMI
All peripheral components are connected to the highway by?
Breakouts (Couplers)
MIL-STD-1553 defines the term Tim division multiplexing as?
Transmission of information from several signal sources through the same line with different signal samples in time to form a composite pulse train.
Q. What are the the 3 MIL-STD-1553 Data words?
Command words, Data Words, Status Words
What is the length of word for a MIL-STD-1553
20 bits in length.
Q. Define Odd parity
Odd parity means there is always an odd number of 1’s in a word.
Data may travel in one way or in two directions what is this called?
Signal can only travel in 1 Direction = Simplex, 2 ways = Duplex
What are the first 3 bits of a MIL-STD-1553 word.
Sync
Bit encoding for the MIL-STD-1553 is based on what format?
Bi-Phase Manchester 2
Define half duplex
When data transmits and receives over the one line but has to wait for its turn for each direction.
What is the transmission technique of the MIL-STD-1553?
Half-Duplex
Maximum number of terminals on a MIL-STD-1553?
31
Transmission media for the MIL-STD-1553?
Twisted shielded pair.
MIL-STD-1773 contains information for?
Fibre optic cabling.
What does ARINC stand for?
Aeronautical radio inc.
ARINC 429 bit encoding?
Bipolar return to zero (RTZ)
ARINC 429 Word size?
32 bits
What are the characteristics of the ARINC 429?
- Data bus using two signal wires
- Word size of 32 bits
- Bit encoding with bipolar return to zero.
- Simplex data bus.
What system does this schematic belong to?
MILD-STD-1553
What system does this schematic belong to? and what does the arrow indicate?
ARINC 429, Arrow indicates simplex
Which graph does this represent?
Return to Zero, No signal is transmitted at the Zero
What is included in a ARINC 429 Word?
Label, SDI, DATA, SSM, Parity
What does the SSM portion of a ARINC 429 word determine?
Validity of the data and a failure warning.
What are the first 8 bits of the ARINC 429 word?
LABEL
Label codes of a word are typically represented as?
Octal Numbers
What is within the LRU of the ARINC 629
Terminal Controller and Serial Interface Module (SIM)
The stub cable is coupled to the global data bus via what on the ARINC 629
Current mode coupler
The ARINC 629 data bus system includes what parts?
Data bus cable, Current mode couplers, Stub cables.
Stub cables are used for?
Bi-directional data movement between LRU and current mode coupler.
The bus cable on a ARINC 629 is?
A pair of twisted wires with a termination resistor at each end.
What is the message structure of the ARINC 629 system?
Message has upto 31 word strings, 4 bit time gap.
Explain the word string of the ARINC 629 system.
Begins with a LABEL and has up to 256 data words.
The ARINC 629 uses a time procedure to prevent accidental mixture, what are the 3 timers?
Transmit interval, Synchronization Gap, Terminal Gap.
Q. The 3 timers of the ARINC 629 system operate in what 2 ways?
Periodic (Standard Mode) or Aperiodic (Abnormal Events Mode)
Which data bus system uses current coupling as the transmission mode?
ARINC 629
Number of terminals on the ARINC 629 system
120
What is the order from slowest to fastest of the Data bus systems?
1553 1MBps = Slowest
429 = Middle
629 = 2Mbps = Fastest
What is the bus architecture of the ARINC 429?
Simplex point to point.
