This article provides a technical overview of the communication protocol AFDX, past, present and future. -AFDX is the newest technology that is used to substitute-ARINC 429. Gradual transition Laitrnt Computing Mboser military commercial projects already implies that the development of the years-AFDX. Yet the set-AFDX official only after the standard-ARINC 664 Part 7 was published on 27 June, 2005. And ARINC-AEEC, working together with industry, have created Dtrministi protocol for real-time implementation of the media Haytrnt, a protocol known among many of the main players in the field today as Hawionika-ARINC 664 Part 7 or AFDX.
The-AFDX interface is designed for critical aircraft, including engines, ie, flight, navigation systems, as well as the systems are considered critical to the operation platform.
Traditionally the-ARINC 429 has been, and still is used, safety-critical application interfaces or platforms Motsot flights, author of critical systems. The-ARINC 429 bus system is Estate Nell”(from”point”), composed in bomb shelters broadcast, with a connection 1 to -1, or 1 to many, the workers at -12.5 Kilohartz or Kilohartz at 100. The-AFDX is designed to substitute for the direct-ARINC 429. However, you can still use on-ARINC 429 low speed applications that run, in collaboration with the rapid movement of AFDX Awionika systems.
Is the standard-AFDX is Aitrnt?
The birth of-AFDX was possible only thanks to the progress of technology and community networks Haytrnt van. Haytrnt fulfilled an important role in creating the most-AFDX media and technological future will Haytrnt.
Showing the switch Haytrnt technology has provided a method of implementing technology to substitute-ARINC 429 Aitrnt the media using the speed of transmitting Aitrnt. Airbus Industries was a company pioneering the-AFDX for the plane-Airbus A380. The fact that other airlines have adopted the same-AFDX promised to long-term success. Community commercial airlines identified the performance benefits and cost savings-AFDX that could contribute to future Hawionika.
The-AFDX, or live Aitrnt Two – way Awionika applications, based on the concepts Aitrnt based on the media of copper or optical fibers and technology Aitrnt switch. However, the very differ-AFDX what – Ethernet 802.3 protocol communication.
AFDX, protocol
The protocol-AFDX planned use of media Aitrnt, but with the characteristics of the ARINC 429, what implies the communication Nell”Estate, the bandwidth is set in advance and redundancy of data when needed, as well as the quality of service based on Kdimoiot. All these help to achieve reconciliation Dtrminizm, a feature particularly important for safety-critical systems that run in real time.
Main characteristics of the AFDX network are Hdtrministi nature of its concept through a number of limitations and improvements in the standard Haytrnt:
Width – Fixed line: limited to – the suspension requirements aggravating ולקליטת data transmission. This implies ownership of the data packet size is set to allow maximum bandwidth guaranteed in advance.
Square packets: packets are the same order in which Sodro.
Double reflection: a double redundancy; two preamble to the data from Sderot.
Virtual Link: approach for implementing a broadcast shelters ARINC 429 using mechanisms Aitrnt”Nell Estate brands. Switches are the most important components on the network AFDX.
The concept of a virtual link (VL) implements a form of the ARINC 429 – a Media Aitrnt of using technology in the AFDX-AFDX. The links are Huirtueliim Connections”Nell Estate Mmsdrim bomb shelters on the network AFDX. Later in this article we will continue to question the use of on-VLs network in Avionics System AFDX.
Considerations on Oritzodim holds-AFDX
Although the movement-AFDX bandwidth is limited, but there are complications related to end-from Sderot Olritzod (jitter). Haritzod is a phenomenon caused the – components of the schedule by arranging the schedule in Hmsdrt end, where the movement of a few square VLs in terms of time scheduled into the-BAG (Bandwidth Allocation Gap – Gap allocation of bandwidth) for the virtual link. Systems to provide end-switches are required to reduce your holds Oharitzod algorithms. To make the explanation simpler Haritzod, demo alone Aotostrada Hmtmzgt of three paths into one path of movement. Haritzod schedule is used to hold the pace of a small flow to achieve the movement and safe square.
Haritzod caused the – component of the schedule (Scheduler) who is trying to transmit all the traffic-VL which should be a gap in the allocation of the bandwidth-VL.
Performance of systems on the edge-AFDX related direct link to multiple links Huirtueliim existing system in the end. All VL transmitter uses a specific bandwidth; can calculate the maximum bandwidth as follows:
Maximum frame size on-VL (1518 bytes, according to A664 part 7)
Bandwidth Allocation Gap (BAG) on-VL (1 to 128 milli-second startup time constant)
That is, for the VL with a BAG of 1 milli-second frame most of 1518 bytes, we can see that is capable of transmit-VL 1,518,000 bytes per second at most.
For VL with BAG of 128 milli-second frame most of 1518 we can see that is capable of transmit-VL 11,859 bytes per second at most.
Compared Laitrnt Hkzvim these extremely low. However, we must remember the-AFDX protocol requires Dtrminizm. Bandwidth Limited holds Oritzodim known in advance, combined with double redundancy, Hdtrminizm provide the necessary safety-critical systems.
Performance Considerations
The performance-VL Bbeitim can be calculated per second. However, the end system may include several VLs broadcast, each of them changed BAG. Therefore, actual performance may actually be affected by problems of Ritzod within the system.
System planners must ensure that the-BAG for all-VLs enable the performance of bandwidth required. If not, issues of Ritzod might affect system performance significantly and make it לבלתי Dtrministit.
Ritzodim may cause serious exception what-BAG. -Scheduler is not allowed to send more than one of any framework within the VL-BAG assigned. If Haritzod causes serious pause, should not be competition or conflicts between frames.
Have made clear, certain scenarios Hashem is not imposed on the-AFDX. For example, when implemented to the system are not aware of too many limitations with the BAG VLs low. This situation could cause serious Lritzodim resulting lack of response on the part of the pilot tool.