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W. Elmenreich, G. Klingler, A. Kößler, S. V. Krywult:
"Time-Triggered Smart Transducer Networks";
Poster: Siemens PSE Technology Day, Vienna, Austria; 25.11.2005.

The availability of small cheap microcontrollers have made it possible to build networks of smart transducers. A smart transducer is the integration of a sensor or actuator element together with a processing facility such as an FPGA or a microcontroller and a standard network interface that allows the access to the transducer data with real-time guarantees. Smart transducers require a small implementation footprint in order to support cheap hardware, and, especially for wireless networks, the power consumption of a node should be low in order to support extented operation time when running on battery. A concise, standardized interface gives access to the requested transducer values while hiding the internal complexity of the transducer thus reducing the complexity at network level.
TTP/A is a time-triggered protocol supporting low-cost smart transducer applications. It has been designed for predictable real-time communication in non-critical applications in the automotive and automation sector. The protocol uses a time division multiple access (TDMA) bus arbitration scheme, which mets timing requirements for typical sensor fusion algorithms. TTP/A implements a unique addressing scheme for all relevant data of a node like communication schedules, calibration data, and I/O properties. This addressing scheme is called Interface File System (IFS). The IFS provides a universal interface to the TTP/A network for configuration and maintenance tools as well as for applications running local on a node. The IFS is structured in a record-oriented format. The smallest addressable unit is a record of 4 bytes. All nodes contain several files with a number of records that can contain information for automatic configuration.