(Ref. Fig. 012)
In case of failure of the processor 1 of the FCU, the processor 2
takes over and all the DMCs receive the same data as those sent by
the processor 1. This loss of redundancy is annunciated on the ECAM
DUs (STATUS).
Briefly, the FCU bus X-A (1A and 2A) conveys the selections of the
CAPT EFIS control section, plus some AFS selections.
The FCU bus X-B (1B and 2B) conveys the selections of the F/O EFIS
control section, the remaining AFS selections, and both the CAPT and
F/O baro reference settings.
The DMC(s) on side 1 uses the parameters from the buses 1-A and 1-B.
The DMC(s) on side 2 uses the parameters from the buses 2-A and 2-B.
(7)
ADF buses
Each DMC receives and processes the ADF1 and ADF2 receiver buses.
In case of failure of a given ADF, the corresponding data are lost
and a flag appears instead.
(8)
VOR buses Each DMC receives and processes the VOR 1 and VOR 2 receiver buses. There is no manual or automatic transfer VOR 1 - VOR 2 for failure cases. In the ND ROSE/VOR mode, the Captain always has the VOR 1 data and the First Officer the VOR 2 data, as regards the course and LATERAL deviation information. But each pilot can select VOR 1 and VOR 2 bearing and station identification data on his ND. In case of failure of a given VOR, the corresponding data are lost and a flag appears instead.
(9)
DME Each DMC receives and processes DME data from both DME interrogators. DME 1 and DME 2 data can be displayed on each ND, but only the onside DME data can be displayed on a given PFD (e.g. DME 1 on the Captain PFD).
(10) ILS Each DMC receives and processes the ILS data (LOC and GLIDE SLOPE deviation signals, ILS frequency, ILS IDENT, ILS COURSE) from both ILS receivers. The ILS 1 data are displayed on the Captain PFD and the First Officer ND and the ILS 2 data on the First Officer PFD and the Captain ND. No transfer is possible (ILS 1 - ILS 2), neither normal, nor automatic.
1EFF : 106-149, 303-399, 1 31-68-00Page 34 1 1 Config-3 Aug 01/05 1 1 1CES 1
FMGC - EIS Bus/DMC Interface
Figure 011
1EFF : 106-149, 303-399, 1 31-68-00Page 35/36 1 1 Config-3 Aug 01/05 1 1 1CES
1
FCU Buses Figure 012
1EFF : 1 1 1CES 106-149, 303-399, 1 111 Page 3731-68-00 Config-3 Aug 01/05
(11)
Radio altimeter Each DMC receives and processes radio altitude data from both radio altimeter transceivers. The DMC on side 1 preferably uses the R/A 1 data, as long as the R/A 1 bus is valid. If the R/A 1 bus is no longer valid, the DMC automatically uses the R/A 2 bus, but it reverts to the R/A 1 as soon as it becomes again valid. If both R/A 1 and 2 buses are invalid, the DMC checks through the two buses at each cycle until a valid one is found. Meanwhile, the red flag RA is displayed on the Captain PFD, only at low altitude (when slats are extended).
(12)
SDAC Each DMC receives and processes both SDAC 1 and 2 buses. The DMC on side 1 works in priority with SDAC 1 data. The DMC preferably uses all the needed parameters from SDAC 1. If one parameter is invalid, the DMC uses that from the SDAC 2. If this parameter is available neither on the SDAC 1 bus, nor on the SDAC 2 bus, a flag is displayed on the affected A/C system image : XXX if the parameter is a digital value. If the parameter is a word of discretes, the corresponding parts of the image (synoptic lines or discrete elements such as pump or valve position) disappear. The DMC(s) which works on side 2 follows the same rules, and also uses preferably the SDAC 1 data.
(13)
FWC data buses (not RS - 422) The FWC 1 and 2 data buses also convey data for A/C system images or for further retransmission by the DMC. The logic for the parameter choice obeys exactly the same rules as for the SDAC.
(14)
ECU (FADEC system) (Ref. Fig. 013) Each Engine Control Unit issues 4 output buses, which always convey the same data 2 by 2 (A1 & A2, B1 & B2). Each ECU is fully redundant : in case of failure of channel A, channel B takes over. Each DMC receives and processes one A bus and one B bus from each engine ECU. The DMCs take the needed parameters preferably on the bus corresponding to the channel in control (word 275, bit 26 = CHANNEL A IN CONTROL, word 275, bit 27 = CHANNEL B IN CONTROL). If a parameter is invalid on one bus, the DMC takes it on the other bus. If this parameter is available neither on the A bus, nor on the B bus, the corresponding indication is either flagged (XX) or removed, depending on the nature of the parameter.
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