TTEthernet

TTEthernet, developed by TTTech Computertechnik AG expands classical Ethernet with services to meet time-critical, deterministic or safety-relevant conditions. It is compatible to standard IEEE 802.3 Ethernet and integrates with other Ethernet networks.As TTEthernet supports communication among applications with various real-time and safety requirements over a network, three different 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.

* 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 a method that is well-known in classical Ethernet networks. 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 less priority than the other two types of messages.

The following picture gives a better understanding of the three types of messages:

TTEthernet will be applied by Honeywell for applications in the aerospace and automation industry [http://www.aviationtoday.com/av/issue/departments/products/20619.html] .

Questions and Answers

* Does TTEthernet extend the existing Ethernet? How does this happen?:TTEthernet sits on top of layer 2 OSI model and below layer 3. Therefore it can be seen as an extension service to existing Ethernet, which provides hard real-time and synchronization capabilities to Ethernet networks. Those services use standard Ethernet frames.
* Are there any standardization efforts made?:Standardization is discussed with different industry organizations. The intention is to standardize those services for use in cross-industry applications.
* Are there patents?:Yes, there are patents held by TTTech Computertechnik AG and Honeywell.

ee also

[http://ethernet.industrial-networking.com/articles/articledisplay.asp?id=2272 | Article about TTEthernet] In "The Industrial Ethernet Book"

[http://www.realtime-ethernet.de | Comparison of realtime-ethernet solutions] Explanations partly German, partly English

References