(b)
Acquisition modules The acquisition modules enable the DMCs to handle all the input signals from the other avionics systems, and to convert them in a suitable format before memorization. If one acquisition module fails, the operation of the other one is not affected.
(c)
Processing channel
(d)
Other functions
1_ Validation/selection
Before processing, the validity of data is checked:
if it is not satisfactory, another source is selected.
2_ Emission
- Data processing: the data memorized in the acquisition
module are processed by the CPU then stored for transmission
via the A629 link, together with some orders to generate the
right image onto the DUs.
- Parameters are sent to the DMC peripherals on an ARINC 429
output bus.
This output bus goes through a hardware switching stage
which enables continuous supply after system
reconfiguration.
1 Switching
_ Downstream of the A629 control logic, a switching enables reconfiguration of the EIS in case of failure of a DMC or a DU.
2 Monitoring
_ Each DU monitors two of the remaining five DUs by comparing the critical parameters value at the DMC relevant input and the value of the same parameters returning on the ARINC 629 feedback bus. When a discrepancy is detected, a message related to the faulty DU is displayed on the monitoring DU and a warning is sent to the FWC.
3 Test function
_ The BITE test is performed in the DMC and the results are stored for later transfer to the CFDS.
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(3) DU description (Ref. Fig. 010) (For further details, Ref. to 31-63-00). The 6 DUs are identical and interchangeable. Each DU receives digital signals from its related DMC through a Data Link (A629) and also through a particular bus (A453) for the weather radar link. These digital signals convey instructions and data corresponding to the displays to be presented on the DUs. The main DU functions are:
-power supply,
-
A629 and weather radar data acquisition,
-
A629 selection,
-image generation and symbols generation,
-weather radar data processing,
-light supply
-feedback signal transmission.
(a)
Power supply Each DU has its independent 115VAC/400HZ power supply. The DUs are supplied from various buses (NORMAL and EMERGENCY A/C network) to ensure redundancy in case of emergency electrical configuration. In that case, only the CAPT PFD DU and EWD DU are supplied. The DUs also receive 28VDC used at initialization.
(b)
A629 and WXR acquisition The data acquisition enables the DU to handle the input signals from the A629 and WXR buses, then convert them to a suitable format before memorization.
(c)
A629 selection
At the acquisition stage, the A629 selection enables EIS
reconfiguration in case of DMC failure.
(d)
Symbol generation Symbol generation is provided by an X/Y matrix behind the screen. The matrix is addressed by complex computation inside the DU which takes its instructions from the data of the incoming valid A629 bus.
(e)
Weather radar processing Weather radar processing mainly consists in converting the radar echoes from sweep signals to screen scan points (X, Y).
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DU - Internal block diagram
Figure 010
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(f) Feedback signal transmission Critical flight parameters are monitored by the DUs through the DMCs. The value of each parameter generated by the graphic generation is transmitted by the ARINC 629 feedback buses to the 3 DMCs.
(4) FCU EFIS control panel
(Ref. Fig. 011) The present paragraph describes the functions of the various control pushbutton switches and selector switches of the FCU EFIS control panels, which enable each pilot to select desired modes or references on his PFD and ND. Both the CAPT and F/O EFIS control panels are identical and give the same display possibilities on the CAPT and F/O PFD and ND. Each EFIS control panel, like the center AFS control panel, supports all the control and indication devices. Each FCU EFIS control panel includes a PFD control part and an ND control part.
(a) PFD control
1_ BARO correction display and hPa/inches of Hg selector knob
This display shows the reference value selected for baro
correction, either in hPa (hectoPascal, 1 hPa = 1mbar) or in
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