*
Reading light panels.
OEUs also send discretes to and get discretes from other systems:
*
Water and waste system
*
Cabin lighting system
*
Smoke detection system for lavatory and crew rest areas.
The configuration database and location of the OEU specifies which discretes each OEU controls.
Data
The OEUs control light driver circuits with data from the ZMU on the EIA-485 data bus. The OEUs send monitored discrete condition and failure status to the ZMU.
The ZMU gets data from other cabin services system (CSS) components and sends it to the OEUs. OEUs use this data to control lights. The ZMU gets data from these items:
EFFECTIVITY
BEJ ALL
*
Intersystem bus
*
Cabin control panel (CCP)
*
Passenger reading light and attendant requests from the in-flight entertainment (IFE) system.
The ZMU gets configuration database and operational software data from the intersystem bus and sends it to the OEUs when necessary.
The first OEU of each column gets a token signal from the ZMU. The OEUs use this signal for software installation.
Discrete Inputs
An OEU can have as many as four discrete and two analog inputs. The passenger service system monitors inputs from the waste tank logic control modules and the lavatory modules.
The waste tank logic control module sends a signal to an OEU when the waste tank for a lavatory group is full. The OEU sends this data to the ZMU. The ZMU then sends a signal to the correct OEU to make a LAV INOP sign come on.
The lavatory module gets a discrete return from an OEU. The lavatory connects the return to the OEU when any of these are set:
*
Call switch
*
Call reset switch
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PSS -OVERHEAD ELECTRONICS UNIT -FUNCTIONAL DESCRIPTION
* Door latch.
The OEU uses the door latch discrete to control the LOCK DOOR and LAV OCCUPIED signs. The LAV OCCUPIED sign comes on only when all lavatory doors in an area are locked. The configuration database specifies the lavatories in an area.
The OEU controls the attendant call light and call reset light with the call switch and call reset switch signals.
Outputs
The configuration database tells each OEU which outputs to use. OEUs can send signals to these units:
*
Passenger information signs
*
Lavatory modules
*
Reading light panels.
Each OEU has these light driver circuits:
*
Six high current outputs -for the lavatory indication lights in passenger information signs or for reading lights
*
Four medium current outputs -for the no smoking and fasten seat belt signs and for the return to seat and lock door signs in the lavatories
*
Two low current outputs -for the call and call reset lights in the lavatories or for row call lights.
The OEUs change 115v ac from the transfer bus to two 28v ac lamp voltage supplies. One output goes to the lavatory module. The other output goes to the passenger information signs and the no smoking/fasten seat belt lights in the reading light panel.
The OEUs change 115v ac from the main bus to 5v ac for row call lights and 12v ac for the reading lights.
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PSS -PASSENGER INFORMATION SIGN LOGIC
General
The passenger address/cabin interphone (PA/CI) controller controls the data for the passenger information signs. It gets information from these units on the left systems ARINC 629 bus:
*
Airplane information management system (AIMS) -airplane altitude and cabin pressure data
*
Electrical load management system (ELMS) -passenger oxygen deployed signals
*
Flap/slat electronics unit (FSEU) -flap handle position
*
Overhead panel ARINC 629 system (OPAS) -flight deck no smoking and seat belts selector positions
*
Proximity sensor electronics unit (PSEU) -landing gear position.
If the PA/CI fails, the cabin system management unit (CSMU) controls the data for the passenger information signs. The CSMU uses the same data from the right systems ARINC 629 bus.
The PA/CI controller or CSMU sends passenger information sign on/off commands to the ZMUs on the intersystem bus.
Fasten Seat Belt
The fasten seat belt signs come on when the flight crew sets the seat belts selector on the flight deck passenger signs module to ON.
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