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EFFECTIVITY
ALL CFM56-5B ENGINES FOR A319-A320-A321
CFMI PROPRIETARY INFORMATION INTERFACES
FAULT DETECTION
& ANNUNCIATION Page 10
Nov 02
CFM56-5B TRAINING MANUAL
ECU SIGNALS
EFFECTIVITY
ALL CFM56-5B ENGINES FOR A319-A320-A321
CFMI PROPRIETARY INFORMATION ECU SIGNALS
FAULT DETECTION
& ANNUNCIATION Page 1 Nov 02
CFM56-5B TRAINING MANUAL
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Two types of data and command values are transmitted between the aircraft systems and the engine controls using dedicated wiring.
Discrete values.
Discretes have one of two values, i.e. on/off, open/closed.
Discretes that supply aircraft configuration data and commands to the ECU are either pin-programmed, or a direct open/closed output of a switch operated by the flight crew, system, or valve.
Examples of discrete inputs from the aircraft include : - Engine position.
- Master lever position.
- Autothrust engagement and disconnect.
The ECU receives discrete inputs from the engine and the ID plug.
Examples of discrete inputs from the engine include : - Overspeed governor switch (HMU).
- Starter Air Valve position switches.
Parametric values.
Unlike discretes, parametric values are not fixed, but can vary over a specified range.
Examples of parametric values include :
- Throttle lever resolver angle (-38.00 - 85.50). - N1 fan speed sensing (0 - 5000 rpm).
- Oil quantity (0 - 100%).
EFFECTIVITY
ALL CFM56-5B ENGINES FOR A319-A320-A321
CFMI PROPRIETARY INFORMATION ECU SIGNALS
FAULT DETECTION
& ANNUNCIATION Page 2
Nov 02
CFM56-5B TRAINING MANUAL
SIGNAL TYPES Analog signals.
The ECU receives and transmits discrete and parametric electrical values through dedicated wiring. These values can be those received from various sensors and switches, or those sent to control engine components, such as torque motors.
Because the values rarely have the same range and vary depending on the particular component, they are known as analog signals.
Digital signals.
Like all computers, the ECU contains logic boards to process the data received and transmitted, but they use a certain kind of electronic signal known as digital.
Much simplified, digital signals are a series of square-shaped waveforms, called data bits. The value of these data bits is described as a ‘1’, or ‘0’. Since a ‘1’, or ‘0’ can also be considered as ‘on’, or ‘off’, most discrete signals are processed as digital signals.
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