SIMULATION OF A CAN-BASED TRACTOR-IMPLEMENT FIELD BUS ACCORDING TO DIN-9684

Modern tractors and implements will be equipped increasingly with elec tronic components together with a field bus for the exchange of inform ation between different tractor and/or implement controllers, task con trollers, and a virtual terminal used for communication with the opera tor. III Germany, a DIN standard (DIN 9684) for such a field bus based on CAN (controller area network) has been developed. The performance of such a system for process control depends on the load of the bus in relation to how messages are transmitted. A simulation program for a field bus based on the DIN 9684 standard has been developed. This prog ram is used to analyse the: influence of the message type used for tra nsfer of setpoints, the procedure by which large amounts of data are t ransferred and the quantity of data on the time required before a setp oint message arrives at its destination. The simulation shows that whe n the setpoint messages are transmitted as ''basic data-process data'' messages, the waiting times will be a few milliseconds. When the setp oint messages are transmitted using ''targeted'' messages, the waiting times can increase to some seconds when, at the same time, large amou nts of data are transferred. Therefore, it is important that the messa ge type is properly chosen. (C) 1997 Silsoe Research Institute.