ISO 11783/SAE J1939 Network Layer

Lecture 6 Network LayerISO 11783 Part 4, J1939-31

BAE 5030 - 353Spring 2009

Instructor: Marvin StoneBiosystems and Agricultural Engineering

Oklahoma State University

Feb 16, 2009 1BAE 5030-353

Purpose of Network Layer

• Defines functionality of network interconnection units– Segment to segment communication

– Network Interconnection Unit tasks• Transfer of messages between segments

– Forwarding– Filtering– Address translation– Re-packaging– Performance statistics

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Network Interconnection Unit types– Repeater

• Bit level repeating from one segment to another (physical layer)

• Adds to effective bus length (propagation delay)

– Bridge• Receives, stores and forwards messages from one segment to

another (data link layer)

• May filter messages

• Maximum recommended transit delay is 50 ms

– Router• May re-map addresses of messages from one segment to

another (network layer)

• Does not allow address claims to pass across

– Gateway• Interconnects ISO 11783 protocol to different protocols (eg.

Ethernet)

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ISO 11783 System

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ManagementComputer

Tractor / Implement Bus

Hitch

Tractor Bus

Implement Sub-network

Engine

TractorECU

Transmission

VirtualTerminal

ImplementECU

Implement ECU andImplement Bridge

ImplementECU

Task ControllerMgt. Computer

Gateway

FileServer

GPSSequenceController

Network Port Identification

• Port Numbering– Each port on a

network interconnection device is numbered for reference. These are standardized in Parts 1 and/or in 4 and 9

Network Layer Message– Purpose

• Acquiring NIU performance statistics

• Setup and management of filter databases

– Control Byte Functions• Filter Database Management ( 7 functions)

– Setup filtering between port-pairs

• Access and Reset General and Parametrics ( 3 Functions)– Access or reset general NIU performance data

• Access and Reset Port-Pair Parametrics ( 3 Functions)– Access or reset port-pair specific NIU performance data

• Topology query (2 functions)– Access Network Topology

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Filter Database Management

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  Command PGN Command Byte

Data

N.MFDB_Request 60672 0 Port_Pair N.MFDB_Response 60672 1 Port_Pair, Filter Mode, [PGN List]N.MFDB_Add 60672 2 Port_Pair, [PGN List]N.MFDB_Delete 60672 3 Port_Pair, [PGN List]N.MFDB_Clear 60672 4 Port_Pair N.MFDB_Set_Mode 60672 5 Port_Pair, Filter ModeN.MFDB_Create_Entry 60672 6 Port_Pair, Filter Mode, [PGN List]

Port Number DefinitionsNumber Definition

0 Local1-14 Assignable15 Global (All ports)

Filter Mode DefinitionsMode Defintion

0 Block specified PGNs (Default = pass all)1 Pass specified PGNs (Default = block all)

2-250 reserved251-255 Defined by ISO 11783 Part 7 or J1939-71

Message sent by transport protocol if needed

Access and Reset Parameterics

Function PGNControl Byte Other Data field

N.GP_Request 60672 128 (80h) Parameter NumbersN.GP_Response 60672 129 (81h) Parameter ValuesN.GP_Reset_Statistics 60672 130 (82h)

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Function PGNControl Byte Other Data field

N.SP_Request 60672 131 (83h) Port-Pair, Parameter NumbersN.SP_Response 60672 132 (84h) Port-Pair, Parameter ValuesN.SP_Reset_Statistics 60672 133 (85h) Port-Pair

General

Port Specific

Access and Reset Parametrics: Parameters

ResetableParameter Number

Number of Bytes Parameter values

0 na Used to request all parameters in numerical order1 2 Buffer Size (bytes)2 2 Max. Filter Database Size (bytes)3 2 Number of Filter Database Entries4 2 Max. Messages Received per second5 2 Max. Messages Forwarded per second6 2 Max. Messages Filtered per second7 2 Max. Transit Delay Time (milliseconds)

* 8 2 Average Transit Delay Time (milliseconds)* 9 2 # Messages lost due to Buffer Overflow* 10 2 # Messages with Excess Transit Delay Time* 11 2 Average Messages Received per second* 12 2 Average Messages Forwarded per second* 13 2 Average Messages Filtered per second

14 4 Uptime since last power on reset (seconds)15 1 Number of Ports

16 – 253 na Reserved for future assignment by SAE254 – 255 na See J1939-71 for definitions

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Parameters:

Topology Query

Function PGNControl Byte Other Data Field

N.NT_Request 60672 64 (40h) Port_PairN.NT_Response 60672 65 (41h) Port_Pair, SA List

Provision to allow network topology to be determined