UP AND DOWN LOADING D/O (3)
GENERAL
The Data loading system includes:
- a Data Loading Selector (DLS) located on the overhead panel to select the target computer,
- a Multipurpose Disk Drive Unit (MDDU) to upload and download data from or to a disk unit,
- a Data Loading Routing Box (DLRB) to route the input/output data between the disk unit and the target computer.
Note: if the MDDU is not installed, up and down loading functions can be performed through a connector by using a Portable Data Loader (PDL). The up and down data loading system is defined as an interface between the onboard computers and the ground-based data processing stations (PCs). The system has two functions, a main uploading function and a downloading function. From a data processing media (3.5 inch disk), the onboard computers use the uploading function to update their databases or to modify part of their operational software (no On Board Replaceable Module (OBRM) on the front face of the computers).
replaceableThe downloading function is used to transfer the data recorded by certain computers during aircraft operation to a 3.5 inch disk. This disk-stored data can be directly analyzed on ground by the airlines.
Note that all the computers involved in the system use the uploading function. Only a limited number also use the downloading function. The Multipurpose Disk Drive Unit (MDDU), the onboard data loader and the onboard computers known as target computers communicate via ARINC 429 data buses. Loading operation is basically controlled by the Data Loading Routing Box (DLRB) by means of the Data Loading Selector (DLS).
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UP AND DOWN LOADING D/O (3)
SYSTEM DESCRIPTION
The Data Loading system is an interface between the aircraft computers and ground data processing equipment used to update software and databases or to retrieve aircraft system data.
DLRB/DLS
The DLRB and the DLS are connected by two RS422 bi-directional serial links (for dialog and maintenance purposes) and two discretes.
The DLS sends user commands to the DLRB and displays the result of these commands on its Liquid Crystal Display (LCD) screen. The list of the computers displayed on the DLS is extracted from the DLRB database. This database must be uploaded to fit the aircraft
configuration (by selecting the DLRB itself in the list of targets).
The DLRB and the DLS only operate in ground condition. When the right hand main landing gear shock absorber is compressed, a discrete signal is sent by the Landing Gear Control and Interface Unit 1
(LGCIU 1) to enable the systems to operate. Note that the DLS
ON/OFF selector switch is used to activate the DLRB through the ON/OFF discrete and not to command the DLS power supply. The DLS power is supplied by the DLRB through the POWER SUPPLY discrete.
LOAD ENABLE
A LOAD ENABLE discrete, depending on the state of the LGCIU 1
discrete signal, is wired to each target computer to enable the loading functions on ground and inhibit them in flight.
TARGET COMPUTERS
The target computers can be separated into two groups. Most of the computers (up to 26) belong to the first group. These computers are connected to the DLRB by two ARINC 429 buses. The DLRB routes the data to be transferred between the MDDU and the computer The three computers belonging to the second group have direct ARINC 429 links with the MDDU. In addition, these computers are internally programmed so that they will not consider the LOAD ENABLE discrete sign
al for downloading operations. As a consequence, for the computers of the second group, the downloading function is also operational in flight.
SYSTEM TYPES
The DLRB/DLS is a type 3 system. Note that the DLS BITE is first processed by the DLRB (via RS422). The MDDU is a type 2 system with the following particularity: instead of a discrete, from the Central Maintenance Computer (CMC) to MDDU, an ARINC 429 bus is required for downloading operations, which is also used by the CMC to activate the MDDU test.

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