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TTEthernet (SAE AS6802) is a computer network technology marketed by TTTech Computertechnik AG "for safety-related applications primarily in transportation industries and industrial automation."〔http://www.tttech.com/technologies/ttethernet/, retrieved 13 July 2014.〕 ==Description== TTEthernet expands classical Ethernet with services to meet time-critical, deterministic or safety-relevant conditions. It claims to be compatible with IEEE 802.3 standards and integrate with other Ethernet networks. Three message types are provided:〔 * Time-triggered messages are sent over the network at predefined times and take precedence over all other message types. The occurrence, temporal delay and precision of time-triggered messages are predefined and guaranteed. The messages have as little delay on the network as possible and their temporal precision is as accurate as necessary. However, "synchronized local clocks are the fundamental prerequisite for time-triggered communication".〔Wilfried Steiner and Bruno Dutertre, (''SMT-Based Formal Verification of a ''TTEthernet'' Synchronization Function'' ), S. Kowalewski and M. Roveri (Eds.), FMICS 2010, LNCS 6371, pp. 148–163, 2010.〕〔 * Rate-constrained messages are used for applications with less stringent determinism and real-time requirements. These messages guarantee that bandwidth is predefined for each application and delays and temporal deviations have defined limits. * Best-effort messages follow the usual Ethernet policy. There is no guarantee whether and when these messages can be transmitted, what delays occur and if messages arrive at the recipient. Best-effort messages use the remaining bandwidth of the network and have lower priority than the other two types. This compares to the eight quality of service classes defined by the IEEE P802.1p task group in 1998 and IEEE 802.1Q added to the standard protocol. In 2008 the company announced Honeywell would apply the technology to applications in the aerospace and automation industry. In 2010 a switch-based implementation was shown to perform better than shared bus systems such as FlexRay for use in automobiles. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「TTEthernet」の詳細全文を読む スポンサード リンク
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