Each computer transmits all its sensor and programming information constantly—as many as signals are floating around the network at any time, whether they're being requested or not. At the same time, each ECU "listens" to the network to pluck out pieces of information it may need to carry out its work. There is no central hub or routing system, just a continuous flow of information that's always available to the ECUs.
Take, for instance, power sliding doors, a common feature on modern minivans. These doors are operated by an ECU called the body control module. Sensors constantly report whether the door is open or closed, and when the driver pushes a button to close the door, the signal from that switch is broadcast across the network.
When the ECU gets that signal, however, it doesn't simply close the door. First, it checks the data stream to make sure the car is in park and not moving. If all is well, it then gives a command to a power circuit that energizes the motors used to close the door. It goes even further, though—the ECU then monitors the voltage consumed by the motors. If it detects a voltage spike, which happens when a door is hindered by an errant handbag or a wayward body part, the ECU immediately reverses the direction of the door to prevent potential injury.
If the door closes properly, the latch electrically locks the door shut. In the old days, this would have been an engineering feat. Just electrically powering the doors would have required dedicated wires running between the shifter, the door switch, and the motor. Before CAN was developed in the mid-'80s, every time an automaker added an electronic feature, like, say, heated seats, new, dedicated wires had to be added just to connect the heaters to a dash-mounted switch.
Over the years, more features meant more wires, until there were literally miles of wire in wrist-thick vines snaking all over the car. With CAN, the seat heaters and the switch that powers them don't have to be directly wired together. They can simply "talk" over the existing CAN network—no special wires needed.
What is needed, however, is some additional programming to get all the devices networked. It's a choice to shift toward programming complexity over physical complexity. CAN has made software development more challenging, but it has had many more positive effects: significant cost savings to the consumer, much lighter weight, reduced reliance on rubber and copper resources, and far better reliability with fewer wires to break over time.
The computer receives information from a many different sensors, including:. Using the information from these sensors, the computer can control things like the fuel injectors, spark plugs and the idle speed to get the best performance possible from the engine while keeping emissions low. The computer can also sense when something has gone wrong and can inform the driver with the "Check Engine" light.
A mechanic can read a diagnostic code from the computer and fix the problem. In other words, a modern luxury car is a rolling computer network. It is amazing how many embedded controllers a car can have. So what was the deal about whether our cars would start on January 1, ? The computers in our cars have no idea what today's date is because it is irrelevant to their calculations. Legal note. New Arona View more. New Ateca View more. Alhambra View more. SUV Range View more.
Charging at Home Relax and reenergise. Solutions for powering up at home. On-street charging Options for recharging while on the move. Accessories Original accessories to suit your personal style. Smaller Businesses Creative and custom solutions for your business. Fleet managers Easy and innovative opportunities for your business.
0コメント