Distributed system architectures based on time-triggered networks guarantee that all electronic systems work together perfectly and meet system design objectives at lower cost in different application domains and industries.

The level of complexity and integration of functions in electronic on-board systems is dramatically increasing.

Networked system architectures need to optimize for multiple objectives such as:

• availability
• reliability
• safety
• integrity
• maintainability

Scalable and flexible COTS network infrastructure is essential for sustainable design of distributed systems which allow mixed criticality functions in one system and satisfy multiple optimization requirements.

Synchronized Operation in Time-Triggered Systems

The term "time-triggered" is closely related to synchronous networks, hard real-time operation and time-driven functions. The majority of real-time and onboard systems are synchronous, due to lower complexity, predictable operation and low resource use. Time-triggered networks create global time at the networking level autonomously, and support synchronized operations of application tasks to global system timing in a distributed system.

Common time base with microsecond accuracy is not dependant on application software or middleware. This simplifies agreement, synchronization and robust partitioning of non-critical and critical functions in distributed and redundant systems. Time-triggered networks with a bandwidth of 100 Mbit/s and more allow integration of robustly partitioned audio/video and critical control data in one network, while time-triggered fieldbuses are designed for distributed control system applications.

The availability of system synchronization greatly supports design of fault-tolerant and high integrity systems and simplifies fault isolation, detection and system recovery, but also enhances the security of the system.

Synchronized operation is essential for efficient design of distributed functions with mixed criticality functions and multiple Quality-of-Service in one network.

Synchronization is also responsible for design of upgradeable and maintainable systems with well defined system interfaces which reduce the system integration costs and effort. Improved system integration is reflected in reduced costs for upgrades, incremental modernization and system reuse.

Support for Asynchronous System Functions and Data Transfers

High-bandwidth time-triggered networks such as TTEthernet fully support asynchronous data transfers whenever time-triggered bandwidth is not used or reserved.

The time-triggered fieldbus TTP allows only a strict time-triggered communication, but it is possible to send asynchronous messages on top of the deterministic network. The time-triggered fieldbus FlexRay supports asynchronous messages in a defined part of the bandwidth after time-triggered traffic.

To get familiar with the terminology in the area of time-triggered systems, have a look at the Easy-to-Read Glossary, which is based on the example above.

For more information about Time-Triggered Architecture, click here.

Click here to see a video of a presentation of Prof. Dr. Hermann Kopetz, the chief architect of the Time-Triggered Architecture.

For more information about TTP, click here.

For more information about TTEthernet, click here.