Cabin Intercommunication Data System (CIDS) PDF

Here is the markdown conversion of the text in the images you sent: # Aviation Australia ## TOPIC 13.21: CABIN INTERCOMMUNICATION DATA SYSTEM ### Introduction Cabin Intercommunication Data System (CIDS) is the core digital cabin management system used in modern aircraft. The requirement for varia...

Here is the markdown conversion of the text in the images you sent: # Aviation Australia ## TOPIC 13.21: CABIN INTERCOMMUNICATION DATA SYSTEM ### Introduction Cabin Intercommunication Data System (CIDS) is the core digital cabin management system used in modern aircraft. The requirement for variable and customised cabin layouts and optional cabin systems has led to a new generation of CIDS. The CIDS is a microprocessor-based system which controls and displays cabin functions for passengers and crew. The CIDS incorporates: * Air conditioning * Communications (cockpit/cabin announcements) * Cabin lighting * Door status indication * Emergency signals * Non-smoking/fasten seatbelt signs * Fire protection/ smoke detectors * Ice protection * Water/waste tank capacity information * Various other customised functions The image is a diagram of the Cabin Intercommunication Data System. It shows how the following systems are connected: Passenger Service System, Passenger Lighted Signs, Passenger Reading Lights, Passenger Calls, Ice Protection, Air Conditioning, Smoke Detection, Passenger Entertainment System, Passenger Address, Automatic Announcement and Boarding Music, Cabin/Service Interphone and Calls, Evac Signal, Safety Precautions, Cabin Lighting Controls and Miscellaneous Door/Slide status, Water/Waste Tank Capacity Information -Test ## CIDS Architecture The CIDS components use the service bus power for normal operation. However, CIDS is connected to the essential bus as well for emergency requirements. The CIDS employs following components to accomplish the functions for passengers and crew: * CIDS Director (DIR) * Decoder/Encoder Unit (DEU A) * Decoder/Encoder Unit (DEU B) * Forward Attendant Panel (FAP) * Additional Attendant Panel (AAP) * Area Call Panel (ACP) * Attendant Indication Panels (AIP) * CIDS Data bus cables ### CIDS Director (DIR) The CIDS Director (DIR) is a central control and interface component of the CIDS. Each DIR has its own Onboard Replacement Module (OBRM). The OBRM used to store the software for current cabin layout and the properties of related equipment. The DIR provides functions of handling of data bus lines, transmission of digital audio signals, controlling of related equipment and systems, programming functions, test initialising and activation of emergency mode. For redundancy the system has two identical Directors (DIRs). One DIR is in hot-standby mode and has the same inputs and outputs as the active one. The hot-standby DIR responds to the inputs in the same way as the active one. Most of the outputs of the hot-standby DIR are disabled. The image is of equipment labelled CIDS Director 1 and 2 The active DIR controls operates and monitors passenger and cabin crew related functions as well as the cabin support systems. For that, the active DIR exchanges data with them through an onboard CIDS network or directly. DIR controls some aircraft systems to activate automatically. The CIDS DIR is connected with the Forward Attendant Panel (FAP) to control the cabin systems and to indicate the status of cabin systems. The DIRs and the related components are interfaced with CIDS data links, ARINC 429 links, discrete signals and audio lines to control individual equipment and systems, programming functions, test initialising and activation of emergency mode. For example, following components are connected with CIDS data links: * Digital Encoder Unit (DEU) type A * DEU type B * Between DIR 1 and DIR 2 Following components / systems are connected with ARINC 429 links: * Flight Attendant Panel (FAP) * Vacuum System Controller (VSC) * Environmental Conditioning System (ECS) * Smoke Detection Control Unit (SDCU) * Centralised Maintenance Computer (CMC) * In-Flight Entertainment system (IFE) * System Data Acquisition Concentrator (SDAC) The image data link block diagram with the top section showing DEU A and DEU B linking to CIDS OP STATUS and the bottom section showing SDCU Channel 1 & 2 the DATA BUS ARINC 429 The DIRs use discrete and audio signals to link with: * Slat Flap Control Computer (SFCC) * Landing Gear Control and Interface Unit (LGCIU) * Engine Interface and Vibration Monitoring Unit (EIVMU) * Cabin Pressure Controller (CPC) * Call panel * Cockpit door * Cabin pressure/Exit signs relay * Flight Warning Computer (FWC) * Audio Management Unit (AMU) * Cockpit handset * Service Interphone Boomsets * In-Flight Entertainment system (IFE) Diagram of discrete and audio signals with items such as FMC1-2, Buzzer off, Service Intph Boomset, CPC 1+2, Signs On, EVMU Oil Press, LGCIU 1+2 LOg In and SFCC 1+2 etc The CIDS Directors (DIRs), Decoder/Encoder Units (DEUs), Forward Attendant Panel (FAP), Additional Attendant Panels (AAPs) and Attendant Indication Panels (AIPs) contain comprehensive Built-In Test Equipment (BITE) circuitry. This allows the CIDS to detect faults in the connected systems. The DIRs store the failure information sent by BITE from these units. The received failures are transmitted to Centralised Maintenance System (CMS) and Centralised Maintenance Computer (CMC) records all failure data. In the event of a major failure, a CIDS caution signal is immediately sent to the respective location. Such as in the airbus cockpit, the failures are indicated on: * ECAM status page * ECAM warning page * CMC-MCDU pages And, it will be indicated on FAP for cabin information. ### Decoder/Encoder Unit (DEU) There are two types of Decoder/Encoder Units and they are named as type A (DEU A) which is used on passenger related systems and the other type B (DEU B) dedicated on cabin related systems and crew functions. The installation-address is identified by coding switches which are installed in each of DEU A and DEU B connection box. Diagram showing Cockpit Controls and Indicating linked to the Director, with the left section showing Aircraft System Functions and the right section showing passenger, crew and cabin functions with the PTP and FAP at the bottom. #### Decoder/Encoder Unit Type A (DEU A) The DEU A data buses interface with active DIR to control passenger related systems such as: * Passenger Service Units (PSU) * PAX lighted signs (FSB/NS/RTS) * PAX-call lights * Loudspeakers * Cabin lighting However, the amount of DEU A requirement and the usage of inputs/outputs on each DEU A depend on the cabin layout, the installation of the optional systems and aircraft type. For example, in A320 has 16 DEU type A, where as in A380 baseline configuration, there are 85 DEU type A installed in the whole cabin (a maximum of 192 can be installed). Diagram showing from director 1 & 2 the PSU with items such as Reading lights and call lights with low voltage differential signalling (LVDS) and DEU A showing DEU connection box ABC BTR and Coding switches to next DEU. The DEUs A are connected to the DIRs through CIDS data bus. For redundancy purposes, there are two top line data buses in each side of left, centre and right. The DEUs A are connected alternately to one of these data buses. All DEU A are interchangeable. The installation address is given through coding switches which are installed in each DEU A connection box. Diagram showing 1 director with OBRM and the top-line data bus feeding DEU A and PTP/FAP #### Decoder/Encoder Unit Type B (DEU B) The interface between the active DIR and the cabin crew related functions is done via Decoder/Encoder Units type B (DEU B). The CIDS uses each DEU B to control: * Area Call Panels (ACP) * Attendant Indication Panels (AIP) * Additional Attendant Panels (AAP) * Handsets * Emergency Power Supply Unit (EPSU) * Slide/door pressure sensors * Drain mast heating monitoring Diagram showing Deu B and PA etc handset RS-232 Not all inputs/outputs are used on each DEU B. This depends on the cabin layout and the installation of the optional systems. All DEUs B are interchangeable. The installation address is given through coding switches which are installed on each DEU B connection box. ### Connection Boxes The CIDS data bus is connected through the connection boxes to all the DEUs. All the connection boxes must be connected. If one connection box is not connected, the data bus is interrupted, and a related message is shown on the FAP/PIM and on the CMC/MCDU. Image showing Connection Box ### Coding Switches The installation address on either DEU A or DEU B is given through coding switches which are installed on each connection box. Image showing the Location of coding switches. ### Forward Attendant Panel (FAP) It is used by the cabin and maintenance crew to control and monitor the various cabin support systems, the passenger and cabin crew related functions. The Forward Attendant Panel (FAP) is connected to the DIRs through ARINC 429 data buses. Through these buses, the FAP transmits data for controlling and monitoring of the cabin systems and receives data from the active DIR for signalling. The FAP transmits its BITE information too. The FAP has links with following CIDS components to control and monitor their performances: * A discrete signal is transmitted to the Emergency Power Supply Units (EPSU) for activation of the emergency lighting. * Discrete signals connect the DEU B for evacuation activation, reset and indication. * The water quantity transmitter provides potable water quantity indication. * The vacuum system controller provides the waste quantity indication. * Discrete signals for lavatory lighting, passenger reading lights and cabin attendant work lights and for activation of the lavatory water heater. * Activation signal for heating of drain mast. Diagram with links to all associated equipment The FAP consists of: * The Programming and Test Panel (PTP) for system indications, programming and testing the CIDS. * Keyboard to controls the cabin systems. * The Cabin Assignment Module (CAM) is the memory module which stores all the cabin related programmable information. Image showing Forward Attendant Panel with the Module CAM The PTP contains an alphanumerical data display and it provides the relevant information sent by the DIR. ### Additional Attendant Panel (AAP) The AAPs have an RS 232 data bus input/output to send and receive data through the related DEU B. It has BITE system to detect internal and external failures. The BITE result is transmitted to the DEU B. Diagram showing DEUB and AAP processing module: The AAP is used to: * To activate EVAC, indication and to reset the system * Reset Pax call * Indication of lavatory smoke and reset function * To control the cabin illumination * To activate lavatory water heaters Image showing the AAP ### Attendant Indication Panel (AIP) The Attendant Indication Panel (AIP) are installed at each cabin attendant station which has a handset. Through the related DEU B the AIP is supplied with 28 VDC and controlled via an RS 232 data bus. Each AIP has a BITE to detect internal failures. The result is transmitted to the related DEU B. The display area for indication of alphanumerical messages is divided into two rows. Each of these rows has 16 characters. The upper line of the display is used for indications related to the cockpit and cabin handset operation. The lower line is divided into 5 sections where text strings can be combined to give passenger call and smoke detection information. The lower line can also be used in its full width to indicate special system information (e.g. PA IN USE). Each individual text is laid down in the Cabin Assignment Module (CAM) and therefore can be programmed accordingly. The back-lit display is off until a command is received from DEU B. The AIP is a display panel with two indicator lights (red and green), which are used to ensure a far-reaching call function, when a related message is displayed. The operation of the indicator lights can be programmed through CAM for each different system functions. The Image shows AIP at calling Station red and Green indicators. ### Area Call Panel (ACP) The Area Call Panels (ACPs) are typically installed on right and left-hand sides of the ceiling at each end of the cabin zone. The fields are used as cabin attendants' attention getters and either they can be programmed to flash or illuminate steadily. The lights can be seen from the front or rear of the ACP. The ACP has four separately controlled fields; each field contains coloured Light Emitting Diodes (LEDs). A call via cabin or cockpit interphone will come on pink on the indicator, a blue light indicates Pax seat call and an amber light indicates a lavatory call. Each ACP links with discrete connections to a nearby DEU B. The DEU B switches the LEDs. Any field or combination of fields can be illuminated. The image is a diagram of the Area Call Panel and location ### CIDS Data Bus Each data bus uses a two-wire twisted and shielded cable. The passenger related systems data buses are connected to DEU A and for the crew related systems data buses are linked to DEU B. The active DIR controls these CIDS data buses. Each data bus cable is terminated with resistors for cable impedance matching and called as Bus Termination Resistors (BTR). They are only available in the last DEU connection box. Data bus diagram: Call panel evac panel, NS/FSB panel handsets over head with middle line linked to DEU B Door. Pressure sensors: slides. pressure sensors with top line linked to Director 1and the top and DEU A, OBRM, Signs, hands sets, cabin lights, EPSU loudspeaker, attend ant indication panel, area call panels. Reading light power units with director A, running to the bottom ptop FAP Top Line The CIDS data bus interface is a bi-directional serial-digital data bus and connected through the connection boxes of all the DEUs. If one the data bus gets interrupted a related message is shown on the PTP/FAP and on the CMC/MCDU. ### CIDS Functions The CIDS provides following functions to accomplish functional control, the testing and the monitoring of the cabin intercommunication data support systems: * Communication * Indicating * Control * Other functions (zone programming, cabin layout selection) Image showing CIDS functions in a box diagram: Cabin crew, cockpit crew, passengers and maintenance, Aircraft and Cabin Support Systems #### Communication Functions The following communication links are achieved through CIDS: * Passenger Address and integrated pre-recorded announcement/boarding music * Cabin interphone * Service interphone * Crew signalling and alerting #### Passenger Address (PA) and Integrated Pre-Recorded Announcement/Boarding Music The PA supplies one-way voice communication to make announcements from the cockpit or from a cabin crew station to the passengers. These announcements are initiated from the cockpit using either a handset or acoustic devices. The CIDS can be interfaced with pre-recorded voice announcements and boarding music system. The cockpit handset is directly connected with active DIR. Pressing the 'Press To Talk' (PTT) switch and talk onto the handset; the announcement is broadcasted over all PA loudspeakers via DEU A or passenger's headsets via In Flight Entertainment system (IFE). The amplifiers are part of the DEU A and individually assigned for passenger or attendant operation. The other acoustic devices are connected to DIR via Audio Management Unit (AMU). The PA transmission key located on the Audio Control Panel (ACP) must be pressed and held. It comes on green and connects the microphone audio to the PA system. 'PA ALL IN USE' indication appears on all AIPs. Also, the cabin attendants can make announcements via cabin crew stations handsets. The cabin attendant's announcements transmit via DEU B to DIR, and then broadcasted over all PA loudspeakers via DEU A or passenger's headsets via In Flight entertainment system (IFE). It is possible to override an established PA announcement either from another cabin station with a higher priority (e.g. chief purser's station) or from cockpit. Diagram with links to all associated equipment. #### Cabin Interphone The cabin interphone system is used for communication between all cabin crew stations or between the cockpit and the cabin crew stations. From the cockpit the communication is established via the cockpit handset or via acoustic device and the cabin the communication is established via any cabin crew station handset. As the communication links are established independently, a certain number of communication links can exist in parallel. Also, conference modes are possible, where more than two interphone sources take part same time. Calls from the cockpit are initiated from the CALLS panel which is connected to the DIRs. The call pushbuttons on the CALLS panel allow the crew to select the attendant station. Connection of the cockpit to the cabin interphone system is done using the 'CAB' key and knob on the Audio Control Panels (ACP). A call started from cockpit to cabin crew or from between crew stations, it activates an aural HI-LO chime at respective crew station loudspeaker to alert the crew member. Also, visual indications are presented on respective AIP and Area Call Panel. Communication between two attendants' handsets can be established via respective DEU B. To initiate a call, take the handset off the hook and then select the required station on the keyboard. When the communication link is established, the relevant station/s DEU/s will initiate the visual indications and aural HI-LO chime. All attendants' stations in the cabin have a RESET key to reset the interphone function, and proceeds to a new dialling. The emergency call or cockpit call overrides all communications between cabin stations. Diagram with links to all associated equipment #### Service Interphone The service interphone system is used for communications between the service interphone stations or between the cockpit and the cabin crew stations. The service interphone jacks are located within the major service areas. This system is available automatically if landing gear down and locked or manually by pressing the 'OVERRIDE' pushbutton. ##### Operation from the Cockpit The acoustical equipment in the cockpit transmits the audio signals to the Audio Management Unit (AMU), through the audio lines. The AMU transmits the signals to the DIR. The DIR transmits the signals to the attendant stations through DEU B and to the service interphone jacks through audio lines. ##### Operation from the Attendant Station The operation starts by pushing the 'INTPH' key on the attendant handset. The audio signals are fed into the CIDS DIRs through the DEU B. The CIDS DIR transmits the audio signals to the cockpit acoustical equipment through the AMU and the service interphone jacks through the audio lines. ##### Operation from a Service Interphone Jack with a Connected Boomset The boomset transmits the audio signals to the CIDS DIR through the audio lines. The CIDS DIR transmits the audio signals to cockpit acoustical equipment through the AMU, the attendant stations through DEU B and the service interphone jacks through the audio lines. Image and diagram of service interphone links #### Crew Signalling and Alerting There are different kinds of cockpit and cabin crew signalling and alerting functions depending on the situation. ##### Area Ready To inform the cockpit crew about the cabin status during takeoff/landing phase. Activated through Flight Attendant's Panels (FAP) the signal which is then displayed on the ECAM. ##### Emergency Crew Alerting System To indicate an unusual behaviour in cabin or cockpit. This function is initiated by alert pushbutton from cabin or from cockpit. ### Indicating and Control Functions The CIDS provides information of performance and operational requirements of the interfaced system on the FAP display. Also, these systems can be controlled via keys on the FAP. #### Indicating Functions The following basic systems are connected to CIDS to monitor these systems and provide indications of their performances on the FAP. * Smoke detection system * Emergency lighting power supply * Ice protection and control * Doors/slides * Vacuum system * Water and waste system The number of different systems can be customised with CIDS according to the requirements. ##### Smoke Detection System The lavatory smoke-detection alert is transmitted through the CIDS and in return CIDS initiates visual and aural warnings on the FAP. Additionally, on the A380 the smoke detectors in the cargo and in the avionic compartments are connected to CIDS to monitor fire protection system. ##### Emergency Lighting Power Supply The CIDS interface with the emergency lighting system for monitoring the system and to carry out battery capacity test. ##### Ice Protection and Control CIDS monitors and controls the protection against the freezing of the potable/waste-water system. The system has a flexible heater foil is bonded to the drain mast tubes and temperature controlled through a sensor. ##### Doors and Slides The door and escape-slide control system monitors the door and escape slide bottle-pressure reservoir at the emergency exits. On the ground and in flight the status is permanently monitored and reported to the FAP and to the CMS. #### Vacuum System / Water and Waste System The CIDS interface the water and waste system via vacuum system to display the potable and waste-water tanks filling level on the FAP. Image of the Water and Waste display along with the location of each button and indicator. #### Control Functions The CIDS fulfils several control functions related to: * Passenger service system * Cabin illumination * EVAC * Passenger lighted signs The number of different systems can be customised with CIDS according to the requirements. ##### Passenger Service System The passenger service system is used for operation of the passenger reading lights and the passenger call activation/deactivation. The controlling switches available for passenger to control these functions. Also, CIDS interface with In-Flight Entertainment (IFE) system to control music, video and games which are accessible at each passenger seat. ##### Cabin Illumination The CIDS controls the illumination of the different cabin areas independently. The system has three illumination levels (BRIGHT, DIM 1 and DIM 2) and can be controlled by pushbutton switches on the FAP. Image of the cabin lighting control panel ##### Emergency Evacuation (EVAC) When the Emergency-Evacuation signalling (EVAC) system is activated either from the cockpit or from FAP or AAP, the system provides aural and visual signals to al crew members giving all necessary preparations for an evacuation from the aircraft. The cockpit EVAC panel directly connected to active DIR, so relevant data is passed to DEU A and DEU B to alert the cabin attendants. If the system is activated through the FAP or AAP, the data flow is through the relevant DEU B and then to active DIR for system activation. Image and diagram showing the EVAC system ##### Passenger Lighted Signs The passenger lighted-signs system controls the No Smoking (NS), Fasten Seat Belt (FSB), Return to Seat (RTS) and EXIT Signs in the cabin and lavatories. The NO SMOKING ON/AUTO/OFF switch in the cockpit controls the NS Signs. They come on manually in the ON position and automatically in the AUTO position if the landing gear is down and locked or slats are extended, and oil pressure is high. When the active DIR receive these signals from respective sensors or computers the relevant data is passed to the all DEU A to activate the applicable passenger sign. If a rapid decompression occurs, the Cabin Pressure Controller (CPC) provides a discrete signal to DIR and activates the NS, FSB and EXIT signs to come on automatically. A passenger attention LO chime is heard through the passenger loudspeakers. Diagram of CIDS and links to other equipment and locations. ### Other Functions The other functions like software loading, cabin section layouts, cabin programming functions, loudspeakers level adjustment and FAP set-up are offered by CIDS. The system reconfiguration is achieved through Field Loadable Software (FLS). These FLS can be loaded in the Onboard Replacement Module (OBRM) of DIRs. #### Software Loading Via a dedicated FAP menu page, the software loading function is available for software loadable CIDS components (Directors, Decoder/Encoder Units etc.). This function is only available on ground. #### Layout Selection The CIDS is designed in such way that, it is not necessary to make complex and time expensive hardware changes if the cabin layout must be reconfigured. It is only to change the software database. The CIDS cabin layout selection function gives the choice of predefined and modifiable cabin layouts which are loaded in the CAM. This function is protected by an access code and is only available on ground. #### Cabin Programming The configuration of cabin zones can be changed via a dedicated programming page on the FAP. Through this page following cabin programming modes are available on ground or in flight. They can be protected by an access code. * No Smoking Zones Programming * Non-Smoker Aircraft Programming #### Loudspeakers Level Adjustment This function is used for manual adjustment of the cabin loudspeakers level for announcements and chimes. This is protected by an access code and available on ground or in flight. #### CIDS Warnings CIDS warnings are annunciated in the cockpit as well as on FAP if DIR detects a failure in the system during the flight. However, the warnings are inhibited during the flight phase of 3, 4, 5, 7 and 8. All BITE results are stored in the DIR's BITE dedicated memory with failure indication shown on the Programming and Test Panel (PTP) and illumination of CIDS caution light on FAP. Same time the BITE information is fed to CMS to store on the CMU memory. Some failures or combination of failures cause immediate indication on ECAM and single chime activation. ##### CIDS warnings on Electronic Centralised Aircraft Monitoring (ECAM) When a CIDS caution message is displayed on the ECAM, the detailed failure message is memorised in the PTP and available on ground on request. The caution messages on the ECAM will displayed on request. The DIR continues to send CIDS caution message to the system until the fault is corrected. The CIDS caution message on the ECAM is displayed even if one DIR fails. #### CIDS warnings on FAP and PTP The CIDS caution light can be reset in flight but comes on again on the ground (landing gear down and locked) if the failure persists. When a CIDS caution light illuminates, the respective failure message is displayed on the Programming and Test Panel (PTP). Image of different equipment and displays with details of what needs to happens when there is a system fault. ### Maintenance Practices #### General Carry out functional tests when called for in the schedule, or when a fault has been reported. This should be done in accordance with procedures laid down in the maintenance manual. The following sequence deals with the PTP on the FAP. After pressing the display ON pushbutton, the first page gives access to 3 main parts: * SYSTEM STATUS to get information on CIDS and on all connected cabin systems * SYSTEM TEST to test CIDS components as well as all connected cabin systems * PROGRAMMING to change the zone and cabin layouts #### System Status The system status function will give the current status of the CIDS been monitored. This includes the CIDS components and the interfaces to other systems. In case of no failure, the message is 'CIDS OK'. In case of failure, the message is indicated first. E.g.: 'SLIDE PRESS LOW'. Selecting the membrane switch next to the failure message gives more details on the related failure. The maintenance page will provide more information on CIDS by presenting last leg report, previous legs report, Line Replaceable Unit (LRU) identification and fault data etc. In flight, only the current leg report item, is displayed and available. Image of the Maintenance page. #### System Test The SYSTEM TEST function is used for the test on ground only. Some of units which can be tested via PTP are listed below: * Active DIR * CIDS data link * DEU A and DEU B * FAP and PTP * AAPS * AlPs * ACPS * Loudspeakers * Sign lamps If there is a failure, it can be read using the automatically displayed SYSTEM STATUS /MAINTENANCE page on the PTP. Test of the hot standby Director is only available via the MCDU. Image of calls a page enabling operational test being performed system ### Programming By selecting the key next to ‘PROGRAMMING' on the main menu, the option is available to select either 'CABIN PROGRAMMING' or 'LAYOUT SELECTION'. Images showing through programming and test panel (PTP) through MCDU #### Cabin Programming For cabin programming, the end seat-row number of each zone must be entered. The no smoking zones can be set in accordance with the respective cabin zones. The 'NO SMOKING' signs in these zones come on steady. Images of CIDS cabin Programming pages ### Layout Selection The cabin layout selection function gives the choice of predefined and modifiable cabin layouts. When activating the CIDS, the last selected layout is loaded from the CAM into the DIR memory. The programmed layouts are marked with a '<'or'>' sign. The number of the last selected layout flashes. A new layout can be selected by pressing the related key and this number then flashes and the layout is downloaded into the DIR. Images layout selections ## Cabin Network Services Introduction The Cabin Network Services (CNS) is a part of the Aircraft Information Network System (AINS) which provides passengers with: * Data communication service * Wireless ethernet/Email services * Telephone and fax facilities * Visual information service such as Airshow * Passenger information network ### Aircraft Information Network System (AINS) The functions of AINS are: * Server providing a host-platform for maintenance and operations applications * Secured interface to the avionics * Virtual link between the Ethernet Local Area Network (ELAN) of the aircraft and the ground-based information system of the airline The internal architecture of this system consists of: * Server Interface Unit (SIU) * Aircraft Network Server Unit (ANSU) #### Server Interface Unit (SIU) The SIU provides an interface between the airline network and the aircraft avionics, to host 'sensible' applications and to accommodate an ethernet switch. The SIU supports the following functions: * Avionics Local Access Network (LAN): an Ethernet switch allows connecting to ethernet LRUS * Input and output labels from avionics LRUS #### Aircraft Network Server Unit (ANSU) The ANSU provides a common data file storage system for loadable software and other applications. A host platform for airline applications processing and network communication services. The ANSU is interfaced with Terminal Wireless LAN Unit (TWLU) for ground network connection with the Cabin Network System (CNS) and with cockpit connections for PC or printer installation. ##### Data communication Service The communication between the end user and the aircraft network server system is handled by data links. This service provides wireless ethernet/email service, telephone and fax facilities in the aircraft cabin area. ##### Wireless Ethernet/Email Services The CNS supplies the aircraft cabin with a high-speed communication connection based on standard ethernet which refers to IEEE 802.3 and standard network protocols. The flight and cabin crew, the passengers and the maintenance personnel can use the CNS system to connect devices like laptops to the LAN. They can use Email services or airline specific applications. To get access