TTP协议培训-010_TTP_Seminar_Bus_comparison_aerospace_new.pdfVIP

Ensuring Reliable Networks Comparison of Aerospace Buses ARINC429, MIL1553, AFDX, TTP Copyright © TTTech Computertechnik AG. All rights reserved. ARINC 429 Ensuring Reliable Networks •ARINC 429: Standard avionics bus from the 1970s. •A dedicated bus is needed for each sender. •A single sender transmits data words periodically or sporadically to multiple receivers. Unidirectional. Therefore not considered as a “real” data bus. •Addition of new nodes causes tremendous cabling effort and HW/SW changes to accommodate new bus interfaces. •Not very scalable. •Single parity bit to check integrity of 32-bit messages at receiver. No other error handling mechanism implemented (possible) at protocol level. •Application is responsible for fault management and usually needs to deal with data from several unsynchronized buses concurrently. •Low certification effort with respect to data bus. Possibly higher certification effort for SW. •In order to overcome scalability problems, bidirectional data buses have been developed. Copyright © TTTech Computertechnik AG. All rights reserved. Page 2 MIL-STD 1553 B Ensuring Reliable Networks •The Bus Controller (BC) directs flow of data on the bus. Requests the transmission and/or reception of data words from Remote Terminals (RTs) by the transmission of a command word. By issuing both a receive and a transmit command, data is transferred from one RT to another. •RTs always answer with a status word, except after broadcast transmissions. Only one node can assume the role of a BC at any time. Dynamic reconfiguration of the BC is possible - but discouraged - through Mode Codes. •If the BC sends its commands in a time-deterministic fashion, message transmission latencies can be determined and RTs can synchronize to t