Multiplexing NACAT 2005

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Multiplexing NACAT 2005

• Sean Bennett
• Centennial College
• Toronto

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Definitions

• Transmitting of digital signals between
  electronic components
• In-vehicle networking
• Sharing of system hardware
• Reduction in system hardware
• Message Identifiers - MIDs

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Historical Perspective

• Used by U.S. Military since 1970s
• MIL-STD-1553 Class A Serial bus
• 1980s most auto OEMs at least 1 bus
• 1980s truck OEMs using proprietary bus
• 1990s truck OEMs using full network serial bus

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Historical perspective cont.

• Automobile OEMs slower to adopt bus networks
  because
• Not cost effective eliminates some wires but
• Replaces them with protocol handling circuits
• Increases competition in U.S. limited number of
  ECM suppliers compared with EU Asia
• Concerns over non-proprietary access to vehicle
  network

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Truck, transit bus, HE OEMs

• Reduction of wiring harness mass
• Networking of parametric hardware TPS
• Increased flexibility of subsystem options
• Reduced factory line assembly costs
• Telemetric access to data bus
• Ability to synergize MID operation
• example engine/ trans/ ABS/ATC/ CWS

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Multiplexing Standardization

• Power line carrier
• J1587/1708
• CAN 2.0 architecture Intel and Bosch
• J1850 automotive
• J1939 heavy-equipment on/off highway
• Lockheed Martin aircraft transit bus

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J1939 and J1850 data bus

• CAN 2.0 platform serial bus
• Class C bus (relates to transaction speeds)
• Speed rated in K/bits per second (b/s)
• Speed window 125 Kb/s up to 1 Mb/s
• Actual example V-MAC III module to EUP module
  500 Kb/s
• High transfer rates mean that real time
  responses are met

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MID requirements

• MID is any controller networked to the bus
• Clock speed rated in MHz
• 1 MHz 1 million bit decisions per second
• J1939 MID clock speeds must be min 16 MHz
• Engine controller clock speeds higher
• FTL-MB 900 module clock speed 24 MHz
• Cat ADEM 2000 clock speed 32 MHz

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Non-serial bus topology
Fuel Injection ECM
Transmission ECM
ABS/ATC ECM
Engine ECM
Chassis Management ECM
Collision Warning ECM
Dash Display ECM
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Serial bus topology
Engine ECM
Transmission ECU
Chassis Management ECM
Instrument Cluster Unit (ICU)
ABS/ATC Module
Twisted Wire Pair Yellow CAN High Green CAN
Low -
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J1939 network MIDs

• Engine controller fuel injection controller
• Bulkhead (BHM)/Chassis (CHM)/Dash ICU
• CWS VORAD Night vision Infrared
• Transmission
• ABS/ ATC/ RPE/ Directional stability
• Climate control
• Telemetry GPS and Satellite 2-way

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Data packet architecture
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FET used as relay in MPlx circuit
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J1939 data bus connectors
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FTL-M2 Module location
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Acknowledgements

• Freightliner Service Training
• Pat Leitner - Freightliner MB, New Jersey
• Joe Bell - Navistar International, Chicago
• Chris Lupini SAE - Delphi Delco
• Artwork from Heavy Duty Truck Systems, 4th
  Edition Delmar Thomson, pub 12/05

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