Simulation of a controller area network-based tractor - Implement data busaccording to ISO 11783

Agricultural machinery in the future will be equipped with a data bus for t he exchange of information between different devices such as a task compute r, virtual terminal, implement controllers, sensors and actuators. This exc hange of information requires standardization. Currently, a working group o f the International Organization for Standardization (ISO) is defining a st andard for a serial control and communications data network for tractors an d machinery for agriculture and forestry and is based on controller area ne twork (CAN) Version 2.0B. A simulation program has been written for a typical agricultural machinery configuration, equipped with data buses, connected to each other. The simul ation program is used to analyse the performance of the network with respec t to the transfer time of messages across the network. The transfer time is determined for different bus loads, priorities of the messages and arrange ment of the devices. The simulations showed that the transfer time of messages across the networ k remains less than 6 ms (maximum observed value) for a typical agricultura l machinery configuration. Increase in load on the implement bus to more th an 80% of full capacity can result in transfer times of about 70 ms when th e priorities are not properly assigned. This transfer time may be too large for some specific applications. When time critical messages are assigned a proper priority, the transfer times of the messages remain less than a few milliseconds, even when the load on the implement bus is high. (C) 1999 Si lsoe Research Institute.