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| ==Description - CAN (Controller Area Network)==
| | For CAN (Controller Area Network) refer to: [[WIS 82.90 On-board Communication System, Multi-function Steering Wheel]] |
| The CAN (Controller Area Network) Bus is a digital computer network which provides:
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| * A digital communication link between multiple Electronic Control Modules (ECM).
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| * Provides message specific addressing.
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| * A two wire, bi-directional communication link with data transmitted according to priority.
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| * The two wire (CAN H and CAN L) method ensures that any interference picked up in the wires is common to both CAN H and CAN L signals and is not "seen" by the receiving module.
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| The W220 has two separate CAN (Controller Area Network) Bus systems.
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| * CAN C - Engine CAN (also known as Chassis CAN) which has fast communication speeds of 125 kbps or 500 kbps.
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| * CAN B - Interior CAN (also known as Body CAN) which has communication speeds of 83 kbps.
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| ===Example - W220 CAN B Network===
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| The CAN B or Interior CAN is also known as Body CAN.
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| [[File:Example_of_W220_CAN_B.JPG|500px|center]] | |
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| ==Issues - CAN (Controller Area Network)==
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| * If one wire becomes faulty the CAN signal should still get through.
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| * If both CAN H and CAN L signals are faulty no communication is possible.
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| ==Diagnosing - CAN (Controller Area Network)==
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| Using the [[STAR Diagnosis System (SDS) or Diagnosis Assistance System (DAS)|STAR DAS]] is the best method to diagnose CAN function.
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| Alternatively, for simple analysis, CAN Signal Levels can be measured using an oscilloscope with respect to 0V or Ground or differentially between CAN H and CAN L at any CAN Bus Connector.
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| '''Warning! Be careful of causing electrostatic damage to electronic components.'''
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| ===Typical Connector - CAN (Controller Area Network)===
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| (Note wire pairs)
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| [[File:Typical_W220_CAN_Bus_Connector.JPG|300px|center]]
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| ===Typical Signal Levels - CAN (Controller Area Network)===
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| * CAN H (High) steady 0.025V when the CAN Bus is dormant (not communicating) and,
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| * CAN H (High) 0.65V amplitude when the CAN Bus is communicating.
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| * Signal data for CAN H is a voltage level going high.
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| * CAN L (Low) steady 11V when the CAN Bus is dormant (not communicating) and,
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| * CAN L (Low) 4.65V amplitude when the CAN Bus is communicating.
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| * Signal data for CAN L is a voltage level going low.
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