[教學] What is CAN Bus?

                        The CAN Bus is an automotivebus developed by Robert Bosch, which has quickly gained acceptance intothe automotive and aerospace industries. CAN is a serial bus protocolto connect individual systems and sensors as an alternative toconventional multi-wire looms. It allows automotive components tocommunicate on a single or dual-wire networked data bus up to 1Mbps.
                       

                                Sincethe early 1940's, automakers have continually improved their vehicles'technology by integrating an increasing amount of electroniccomponents. As technology progressed, the vehicles became more complexas electronic components replaced mechanical systems and providedadditional comforts, convenience, and safety features. Up until therelease of CAN Bus, vehicles contained enormous amounts of wiring whichwas necessary to interconnect all of the various electronic components.
                       

                        Dueto the vast amount of wiring, an after market installation requires theinstaller not only to understand how the integrated systems communicatewith each other, but also requires numerous connections to be madethroughout the vehicle. To make matters worse, the vehicle wiringdiffers between vehicle years, makes, and even models. As a result,installers need to be highly knowledgeable and perform intensive laborfor the most trivial after market equipment or the installation shopexperiences countless hours of lost time on troubleshooting andsometimes even expensive claims for damaged OEM equipment. During thisprogression, installation shops have had an increasingly difficult timefinding qualified staff that are able to perform everyday installationsand as a result, have either had to increase their prices to compensatefor the required specialization and labor, or simply had to turn awaythe customers who owned complex vehicles.
                       

                                TheBMW 850 coupe was the first CAN Bus vehicle to enter the market in1986. By reducing the vehicles wiring by 2km, the vehicles overallweight was significantly reduced by at least 50kg and using only halfthe connectors. For the first time, each of the vehicles systems andsensors were able to communicate at very high speeds (25kbps - 1Mbps)on a single or dual-wire communication line as opposed to the previousmulti-wire looms. However, the introduction of CAN Bus also increasedthe vehicles complexity and made after market installations even moredifficult and in many cases impossible to perform.
                       

                                In2006, over 70% of all automobiles sold in North America will utilizeCAN Bus technology. Beginning in 2008, the Society of AutomotiveEngineers (SAE) requires 100% of the vehicles sold in the USA to usethe CAN Bus communication protocol while the European Union has similarlaws. Several new after market devices have been introduced into themarket that utilize the CAN Bus protocol but until now, there have beenno new devices that assist the aging after market remote starter andalarm system technology. Now there is an after market module thatoffers remote starter and alarm connectivity to the CAN Buscommunication protocol.