Applications - CAN System Engineering - page 264

Fig. 5.8 Time-triggered
controller area network
(TTCAN)-based X-by-wire
prototype

Networking is already an old story: aircrafts have been using ARINC 429 since
30 years. Why then a change towards a “non-avionics” network as CAN?

5.3.1.1 From ARINC 429 to CAN

First of all, a few words on the Aeronautical Radio Incorporated (ARINC) label:
The Airlines Electronic Engineering Committee (AEEC) is an international
standards organization, comprising major airline operators and other airspace users.
The AEEC establishes consensus-based, voluntary form, fit, function and inter-
face standards that are published by ARINC and are known as ARINC Standards.
ARINC Standards specify the air transport avionics equipment and systems.
ARINC 429 is very well defined and largely used and known communication
system. The first specification was delivered in 1977.
The physical layer is robust to the aeroplane environment and is characterized
by:

• Rreturn-to-zero (RZ) bipolar modulation and tri-state modulation consisting of
“HI,” “NULL” and “LO” states,
• Nnominal voltages values as described in Table 5.1 and
• Cables and nodes with 75 Ω impedance.

Nevertheless, main drawbacks have limited the application and increased wires:

• It has a low bit rate, with high-speed operation at 100 kbits/s and low-speed op-
eration around 12 kbits/s.
• Labels (equivalent to CAN identifiers) are too strictly defined.