DATA BUSES (ASCB D AND LAN)
All the units of the PRIMUS EPIC® system use the virtual back plane
network to send data between each other. The virtual back plane network
contains:
• the Avionics Standard Communication Bus version D (ASCB-D)
• the software and the hardware necessary to send and receive data on
the ASCB-D
The MAUs, the Display Units (DU) and the Modular Radio Cabinets (MRC)
are directly connected to the Avionics Standard Communication Bus version
D (ASCB-D) to distribute data.
The ASCB D is a high-integrity bi-directional digital data bus and consists of
four individual buses, two for LH (copilot side) units and two for RH (pilot
side) units, providing dual redundancy in data distribution.
Each unit connected to the ASCB-D contains the software and the hardware
necessary to send and receive data on the ASCB-D: this is typically named
Network Interface Module (NIM).
The corresponding module in the MAU is instead named Network Interface
Controller (NIC) since it governs the whole ASCB-D data flow.
MAU 1, MRC 1 and the copilot’s DUs (DU 1 and DU 2) are interconnected
by the LH (Main) ASCB-D and by the LH Backup ASCB-D.
MAU 2, MRC 2 and the pilot’s DUs (DU 3 and DU 4) are interconnected by
the RH (Main) ASCB-D and by the RH Backup ASCB-D.
The two LH and RH (Main) ASCB-D buses cross-feed data to the opposite
side units.
A Local Area Network (LAN) is installed for data loading, maintenance and
test functions.
The LAN interfaces the same modules as the ASCB-D plus the CMC
(Central Maintenance Computer) module of MAU 1.
Maintenance is carried out on the ground by connecting a computer to the
LAN. This allows:
• to upload database files and/or software to the system
• to download data or fault history files