The AFDX stands for avionics full duplex, a communication system used by both Airbus and Boeing for the latest aircraft. It was developed by Airbus mainly for A380 jetliner and later used in its A400 and A350. Boeing use it for B787. It is also known as arinc 664 part 7. It is replacing the arinc 429 and 629. The 429 offers point to point communication in its simplex data communication which is not suitable as the number of systems and LRUs had grown significantly. The 629 offers half duplex communication with full expansion potential, however it requires special interfaces and equipment, thus, it is costly.
Ethernet is the most common communication system used in the commercial computers it the LAN system, but it suffers the two main disadvantages. It works on data packages and there are instances of missing data. Secondly, it is limited ability in its to control and schedule the communication timing, thus it is NOT suitable for system that requires immediate action/ responses such as the flight control system.
The communication system of the avionics requires:
- guaranteed real time operation.
- support repetitive data such as the altitude and latitude.
- support file data such as used for database and video.
The AFDX is designed based on the ethernet technology with the added features to:
- ensure real time communication
- enable sampling messages
- enable queuing and SAP messages.
The system group the packages into three different types of data such as sampling and queuing. Each package on each VL will have sequence number to ensure all data are received and no duplicate data are used twice.
To make it real time, the sources and destinations are predetermined, this easier as the aircraft systems are closed systems where the users are predetermined.This is done by using the concept of virtual virtual links where a transmitter may talk to multiple receivers, like the concept of ARINC 429.
DIAGRAM to be added
There 3 VL here...
T1 ==> R1
T1 ==>R2
T1 ==> R3
Virtual links can only have 1 source, and they are simplex.
Each VR is allotted the BAG ( bandwidth allocation gap) such as 1st, 2nd, 3rd .... 128 millisec. It there are more than one receivers, the AFDX will keep the signal as buffer.
The jitter is the time different between the transmission and receiving.
The BAG determine the timing and the frequency of the link, but not the contents. The contents is designed as per ARINC 653.
Redundancy - It is a concept designed for safety of the system. The data is transmitted in 2 different network.The first valid frame received will be used and the second data will be ignored.
Resources:
http://youtu.be/LxTVxz5ogag
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Additional Information.
1. ARINC 664 consists of 8 parts. They are...
a. systems concept and overview
b. ethernet physical and data links layers.
c. internet based protocol and services.
d. address structure and numbers.
e. network domain and interconnect
f. network management
g. AFDX
h. Operation with non-IP protocols and services
Ethernet is the most common communication system used in the commercial computers it the LAN system, but it suffers the two main disadvantages. It works on data packages and there are instances of missing data. Secondly, it is limited ability in its to control and schedule the communication timing, thus it is NOT suitable for system that requires immediate action/ responses such as the flight control system.
The communication system of the avionics requires:
- guaranteed real time operation.
- support repetitive data such as the altitude and latitude.
- support file data such as used for database and video.
The AFDX is designed based on the ethernet technology with the added features to:
- ensure real time communication
- enable sampling messages
- enable queuing and SAP messages.
The system group the packages into three different types of data such as sampling and queuing. Each package on each VL will have sequence number to ensure all data are received and no duplicate data are used twice.
To make it real time, the sources and destinations are predetermined, this easier as the aircraft systems are closed systems where the users are predetermined.This is done by using the concept of virtual virtual links where a transmitter may talk to multiple receivers, like the concept of ARINC 429.
DIAGRAM to be added
There 3 VL here...
T1 ==> R1
T1 ==>R2
T1 ==> R3
Virtual links can only have 1 source, and they are simplex.
Each VR is allotted the BAG ( bandwidth allocation gap) such as 1st, 2nd, 3rd .... 128 millisec. It there are more than one receivers, the AFDX will keep the signal as buffer.
The jitter is the time different between the transmission and receiving.
The BAG determine the timing and the frequency of the link, but not the contents. The contents is designed as per ARINC 653.
Redundancy - It is a concept designed for safety of the system. The data is transmitted in 2 different network.The first valid frame received will be used and the second data will be ignored.
Resources:
http://youtu.be/LxTVxz5ogag
---------------------------------------------------
Additional Information.
1. ARINC 664 consists of 8 parts. They are...
a. systems concept and overview
b. ethernet physical and data links layers.
c. internet based protocol and services.
d. address structure and numbers.
e. network domain and interconnect
f. network management
g. AFDX
h. Operation with non-IP protocols and services
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