Enabling powerful GUIs in ISOBUS networks by transparent data compression

a r t i c l e i n f o As the functionality of ISOBUS compliant agriculture machines increases, demands on the underlying bus network capacity increase as well. Therefore, to prevent potential bottleneck performance of critical applications, bus utilization must be carefully optimized. In this paper, a methodology for transparent compression/decompression of Object Pool files arising from the use of powerful GUIs during network initialization time is presented. Comprehensive simulation experiments developed under CANoe.ISO11783 shows that data compression remarkably reduces bus utilization during ISOBUS network initialization time, thus enabling the use of powerful GUIs. Furthermore, simulation results suggest GZIP as the best performing method for transparent ISOBUS data compression. The number of electronic components over agricultural equipment has increased significantly [3] during the last years. This process has generated the need of a standardized agricultural Binary Unit System (bus). A bus is a bandwidth limited communication resource shared by agricultural systems, including tractors, implements and farm computers from different manufacturers that is used for information transmission purposes [16]. The development of the bus concept in agriculture is accomplished by the ISO 11783 standard [8], best known as ISOBUS, which specifies a serial data network for control and communication on agricultural tractors and implements. The ISOBUS standard somewhat resembles the Open System Interconnection (OSI) standard developed in the mid-1990s for the open interconnection of data networks [9]. Briefly, the purpose of ISOBUS is to standardize the method and format to data exchanging between specific electronic systems including sensors, actuators, control elements, information storage, and display units mounted on tractors or implements. An ISOBUS network [17] is built from a number of Electronic Control Units (ECUs) which are interconnected through a CAN 2.0b [2] bus, working at 250 Kbits/s. Among the connected ECUs, some of them are designated to carry out very specific tasks such as the Task Controller (TC) and Virtual Terminal (VT) units. The VTs have a graphical display with I/O interfaces to make possible the external operator interaction. The VT functionalities (described in part 6 of the ISO 11783 standard, hereafter ISO 11783-6) are specified by the behavior of a set of objects, each of them characterized by a set of specific attributes. In addition, the VT interface of any reachable ISOBUS device is defined through a set of objects called Object Pool (OP). Multiple ECUs might concurrently transmit multiple OPs to a VT during ISOBUS network …