CFM56-5B TRAINING MANUAL
DIGITAL SIGNAL INTERFACES ARINC429 databuses.
Digital communication between the aircraft and the engine is in the form of a serial group of 32 data bits arranged in a predefined order (ARINC429 protocol), that can be considered as a coded sentence.
This coded sentence is known as a 32-bit digital ‘word’. The word is transmitted, or received through ARINC429 databuses.
32-bit words.
Each 32-bit word is made up of 5 sections that serve different purposes :
- The section using bits 1-8 is known as the label and is used to categorize the word, corresponding to ARINC429 definitions.
- Bits 9 and 10, are used as the Source/Destination Identifier (SDI).
i.e. The source could be the name of the computer transmitting the data.
- The data section is made up of bits 11 to 29.
i.e. Parametric, or discrete values put into digital format.
- Bits 30 and 31 are used for the Status Matrix (SM),
which indicates the data word condition and validity.
- Bit 32 is the parity bit. ARINC protocol requires that the sum of ‘1’ bits contained in the word must be an odd number, so the parity bit is set to either a ‘1’, or ‘0’ as necessary.
EFFECTIVITY
ALL CFM56-5B ENGINES FOR A319-A320-A321
CFMI PROPRIETARY INFORMATION ECU SIGNALS
FAULT DETECTION
& ANNUNCIATION Page 6
Nov 02
CFM56-5B TRAINING MANUAL
11 0 0 1 0 0 0 1 0 0 0 0 0 0 1 0 1 0 0 0 0 1 0 1 0 1 0 1 1 1
313029282726252423222120191817161514131211109 8 7 6 5 4 3 2 1
P : PARITY (ODD)
SM : STATUS MATRIX (DATA CONDITION/VALIDITY) SDI : SOURCE/DESTINATION IDENTIFIER
LABEL : WORD-TYPE IDENTIFIER
CTC-231-013-00 ARINC 429 MESSAGE
EFFECTIVITY
ALL CFM56-5B ENGINES FOR A319-A320-A321
CFMI PROPRIETARY INFORMATION ECU SIGNALS
FAULT DETECTION
& ANNUNCIATION Page 7
Nov 02
CFM56-5B TRAINING MANUAL
ECU INPUTS
Each ECU channel receives critical engine signal inputs from separate sources.
Dual inputs :
LVDT/RVDT and resolver :
- VSV, VBV, TBV, LPTC, HPTC, FMV.
Valve position switches :
- SAV, FRV, BSV, HPSOV.
PS12.
PS3. P0.
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