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Controller Area Network (CAN)

Vi-PEC ECUs support up to two independent CAN modules

What is CAN?

Controller Area Network (CAN) is a communications bus protocol designed for multi-device communications in electrically noisy environments. CAN allows many devices to be connected to the same two wire bus. CAN is found in numerous factory vehicles and is supported by many after market devices such as dash displays. Vi-PEC VX ECUs support up to two independant CAN modules.

Note: Vi-PEC VX ECUs support a user configurable CAN bus from FW version 4.8.0.

Note: All Vi-PEC VX ECUs after serial number 10000 support CAN. ECUs with older serial numbers will need to be returned for a minor hardware change to enable the CAN module.There may be a charge for this service.

CAN Bus Basics

Physically a CAN bus consists of a pair of wires labelled CAN H and CAN L. Each device on the bus “taps” off these two wires. These wires are twisted along their length and terminated at each end with terminating resistors.Twisting and terminating resistors are essential to ensure correct signal integrity on the bus. The following diagram illustrates the minimum CAN bus:

Each device on the bus transmits in units called “Frames.” Frames are small messages that have a “CAN Identifier” (CAN ID) and some data. CAN is a broadcast bus. This means that when one device transmits a frame, all other devices can receive that frame.The rule on the bus is that only one device is ever allowed to transmit a particular CAN ID. So as long as no two devices are set up to transmit on the same CAN ID then everyone is happy.

The data carried with each CAN frame is the useful part of the frame that allows us to spend parameters such as engine speed. Frames can contain more than just one parameter and lots of frames can be sent one after the other to transmit a longer data stream.

As all devices are on the same bus they must all talk at the same data rate. Most devices have a selectable data rate. Just make sure all devices on the bus are set to the same rate (e.g. 1MBps).

To get data from one device to another, you must define the CAN ID that the sending device will transmit its data on. Then the receiving device must be configured to listen to that CAN ID and use the data appropriately. It is not always possible to configure both the transmitting and receiving devices. Usually one device has a fixed setup (usually the receiver) and the transmitter must be configured as specified by the receiver’s manufacturer.

For more in depth information search Controller Area Network on the internet or refer to CAN on Wikipedia.

Features

The Vi-PEC CAN feature is having the choice between PlugIn connection for speedy installation or custom looming.

Choose either:

  1. Bayonet connect, pre terminated, CAN cables or
  2. WireIn CAN cabling components

Installation and Wiring

Custom wiring of a CAN bus requires advanced knowledge of communications wiring techniques. It is recommended to use PlugIn wiring solutions where they are available. Refer to the Vi-PEC Wiring and Installation Manual for further information on ECU wiring. Also refer to each of the CAN devices' installation manuals.

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