1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.TO PLACE A DOCUMENT ORDER: (724) 776-4970 FAX: (724) 776-0790SAE WEB ADDRESS http:/www.s
3、ae.orgCopyright 2000 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001RECOMMENDEDPRACTICEJ2366-2ISSUEDNOV2001Issued 2001-11Link LayerTABLE OF CONTENTS1. Scope . 42. References . 52.1 Applicable Publications 52.1
4、.1 SAE Publications 52.2 Related Publications . 52.2.1 SAE Publications 52.2.2 CAN Publication . 52.2.3 ISO Publication. 53. Definitions. 53.1 ATID . 53.2 Bit . 53.3 Clear. 53.4 Collision 53.5 Controlling Layer 53.6 Dominant 53.7 Frame . 53.8 FrameCollisionCounter Threshold, FCCThreshold 63.9 Halt S
5、tate 63.10 HDLC 63.11 IDB and IDB-C 63.12 Insane Node . 63.13 ITS 63.14 Key State 63.14.1 Key Off State 63.14.2 Key On State 63.14.3 Key Pulse . 63.15 LLC (Logical Link Control) 63.16 MAC (Media Access Control 63.17 Node. 63.17.1 Active Node 73.17.2 Not Active Node . 73.17.3 Not Present Node. 7SAE J
6、2366-2 Issued NOV2001-2-3.17.4 Quiescent Node 73.18 Octet .73.19 OSI73.20 PDU (Protocol Data Unit)73.21 Power Mode State 73.22 Quiescent Network .73.23 Random 73.24 Recessive .73.25 Set 83.26 Time Intervals .83.26.1 Activity Timer, TStartActivity.83.26.2 Wait Timer, TWait.83.26.3 Actual/Measured Tok
7、en Hold Time, T TokenHoldActual 83.26.4 Inter-Frame Maximum Delay, TInterFrame 83.26.5 Token Hold Period Start Interval, TStartTHP.83.26.6 My Token Hold Period Start Interval, T MyStartTHP .83.26.7 Network Inactivity Time TNoActivity.83.26.8 Lost Token Recovery Time TLostToken 83.26.9 Maximum Token
8、Hold Time, TTokenHoldMax 93.26.10 Maximum Token Rotation Time, T MaxRot93.26.11 Node Inactivity Maximum, TInactive93.26.12 Node Removal Timer, TNodeRemove 93.26.13 Power Mode Status Change Time Interval, TKeyOnOff 103.26.14 Bus Reset Time, TResetPeriod 103.26.15 Token Hold Time, TTokenHold 103.26.16
9、 Transmission Duration Time, TTxDuration. 103.26.17 Maximum Transmission Duration Time, T MaxTxDuration. 103.27 Token 103.28 Token Holder 103.29 Token/Done Frame. 103.30 Token/Start Frame 104. Environment104.1 IDB-C Node Hardware Requirements. 104.2 IDB-C without Gateway to OEM Data Bus .114.3 IDB-C
10、 with Gateway to OEM Data Bus 115. Protocol Overview . 125.1 Physical Bus Detection. 135.2 Logical Network Architecture 135.2.1 Virtual Token Bus . 135.2.2 Dynamic Address Allocation . 135.2.3 Power Mode Detection and Generation 135.2.4 Frame Flow Control 135.2.5 Node Removal Detection 145.2.6 Lost
11、Token Detection 145.2.7 Runaway/Insane Node Detection and Recovery 145.2.8 Recovery from bus contention following extended period of no activity .145.2.9 Recovery from bus contention when the T NoActivity timer has not expired 145.2.10 Enabling CAN Frame Filtering 155.2.11 Transmission Order of CAN
12、Frames.155.2.12 Link Level Diagnostics 15SAE J2366-2 Issued NOV2001-3-6. Link Layer Frame Format . 166.1 CAN Frame Format, Objects, and Elements 176.1.1 Loss of Arbitration. 176.1.2 Frame Acknowledgement . 176.1.3 Remove Frames .176.1.4 Extended Frame (29 Bit Identifier) Element definition 176.2 Arb
13、itration and CAN Error Handling 186.2.1 Transmitting Node Loses Arbitration 186.2.2 CAN BIT ERROR 186.2.3 CAN STUFF ERROR 186.2.4 CAN CRC ERROR . 186.2.5 CAN FORM ERROR .186.2.6 ACKNOWLEDGMENT ERROR 186.3 Media Access Control (MAC) Sub-layer . 186.3.1 MAC Field Definitions . 196.3.2 MAC Frame Defini
14、tions. 196.4 Logical Link Control (LLC) Sub-layer 276.4.1 Frame Field Definitions . 276.4.2 LLC DATA Frame containing SAE J2366-4 Data .286.4.3 LLC DATA Frame containing Other Data . 286.5 SAE J2366-2 Protocol Sequences . 296.5.1 Initialization . 296.5.2 Active State . 316.5.3 Get Token State 326.5.
15、4 Have Token State . 346.5.5 SendFrame Function 356.5.6 ReceiveFrame Function 366.5.7 InboundFrame Function 36Appendix A Halt State Processing . 38Figure 1 Scope of SAE J2366-2 .4Figure 2 Example IDB-C without OEM Data Bus 11Figure 3 Example IDB-C with OEM Data Bus.12Figure 4 Mapping of SAE J2366-2
16、on CAN 2.0B 16Figure 5 Link Layer Frame Format . 17Figure 6 MAC Sub-layer Frame Format 18Figure 7 MAC BUSRESET Control Frame Format . 20Figure 8 MAC DEVRESET Control Frame Format . 21Figure 9 MAC JOIN Control Frame Format 22Figure 10 MAC JNAK Control Frame Format . 23Figure 11 MAC LEAVE Control Fram
17、e Format .24Figure 12 MAC STATUS Control Frame Format 25Figure 13 MAC STATUSREQ Control Frame Format.26Figure 14 LLC General Frame Format 27Figure 15 LLC Other (non-SAE J2366-4) Data Frame Format . 28Figure 16 Initialization Sequence30Figure 17 Active State Sequence . 32Figure 18 Get Token State Seq
18、uence 33Figure 19 Have Token State Sequence 34Figure 20 SendFrame Function Sequence . 35Figure 21 ReceiveFrame Function Sequence 36Figure 22 InboundFrame Function Sequence 37SAE J2366-2 Issued NOV2001-4-Table 1 Physical Node ID Transmission Values7Table 2 Token Hold Time Maximums 9Table 3 CAN Elemen
19、ts 17Table 4 MAC Frame IDs Defined . 191. ScopeThis SAE Recommended Practice details the Link Layer of the Intelligent Transportation Systems(ITS) Data Bus, which is generally intended for in-vehicle use.The ITS Data Bus (IDB) is a non-proprietary token passing bus, designed to allow disparate consu
20、mer,vehicle, and commercial electronic components to communicate and share information across a standard,open data bus. This first version of the IDB is called IDB-C.This Recommended Practice describes the Link Layer of the IDB-C, as shown in Section 1. Below the LinkLayer of the IDB-C is the CAN 2.
21、0B Link Layer. The Physical Layer of the IDB-C incorporates the PhysicalLayer as specified by SAE J2366-1 and J2590.FIGURE 1SCOPE OF SAE J2366-2The IDB-C Link Layer is logically divided into two functional sub-layers, viz., Logical Link Control (LLC) andMedia Access Control (MAC). However, these are
22、 logical groupings that re-use some of the same bits withinthe CAN 2.0B frame for efficiency.The MAC sub-layer handles all media access functions, such as virtual token handling, addressing, andnotifications of IDB-C configuration changes to other MAC layers on the IDB-C.The LLC sub-layer provides t
23、he mechanisms to send and receive point-to-point or broadcast frames to otherLLC sub-layers on the IDB-C. In addition, the LLC provides an Alternate Transport Identifier (ATID) allowingmore than one set of higher layer protocols to be used on a single Node.SAE J2366-2 Issued NOV2001-5-2. References2
24、.1 Applicable PublicationsThe following publications form a part of this specification to the extent specifiedherein. Unless otherwise indicated, the latest issue of SAE publications shall apply.2.1.1 SAE PUBLICATIONSAvailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001, http:/www.sa
25、e.org.SAE J2366-1ITS Data BusPhysical LayerSAE J2590PMODE for In-Vehicle Networks2.2 Related PublicationsThe following publications are provided for information purposes only and are not arequired part of this document.2.2.1 SAE PUBLICATIONSAvailable from SAE, 400 Commonwealth Drive, Warrendale, PA
26、15096-0001, http:/www.sae.org.SAE J2355ITS Data BusArchitecture Reference Model Information ReportSAE J2366-4ITS Data BusThin Transport LayerSAE J2366-7ITS Data BusApplication Message Layer2.2.2 CAN SPECIFICATIONAvailable from Robert Bosch GmbH, Postfach 50, D-7000 Stuttgart 1, Germany.CAN Specifica
27、tion, Version 2.0B2.2.3 ISO P UBLICATIONAvailable from ANSI, 25 West 43rd Street, New York, NY 10036-8002.ISO 7498:1990Information processing systemsOpen system interconnectBasic reference model3. Definitions3.1 ATIDAlternate Transport Identifier. This identifies which protocol is to be used to deco
28、de the protocol datapacket portion of the frame.3.2 BitA signaling unit or unit of data transmission of minimal length. It can hold either the value 0B or 1B.3.3 ClearThe word “clear” is used in referring to one or more bits to indicate that they each have a value of 0B.This is also referred to as “
29、dominant” in CAN 2.0B terminology.3.4 CollisionA collision occurs when two or more Nodes attempt to transmit data on the networksimultaneously. This results in the transmissions interfering with each other. On a CAN bus, one of the collidingNodes “wins”, and its data appears on the bus. Other Nodes
30、back off and retry their transmission.3.5 Controlling LayerThe Controlling Layer is that hardware, software application, or protocol layer responsiblefor determining if and when the Node should join or leave the network.3.6 DominantA term defined in CAN 2.0B to indicate a data bit with a value of 0B
31、.3.7 FrameAn ordered sequence of octets, used to communicate information between the Link Layers of IDB-CNodes.SAE J2366-2 Issued NOV2001-6-3.8 FrameCollisionCounter Threshold, FCCThresholdMaximum number of non-JOIN, JNAK, STATUSREQframes the Token Holder shall accept within its own token hold perio
32、d from any given Node. If the TokenHolder receives more such frames from a given Node, it shall queue a DEVRESET frame to that Node.FCCThreshold is set to 1. The FrameCollisionCounter is incremented whether TNoActivity expired or not. IfTNoActivity expired, reception of one non-JOIN, JNAK or STATUSR
33、EQ frame is normal, because of networkcontention. But if further frames are received from any Node, this means that the sending Node did notrecognize the proper Token Holder. It is therefore requested to reset immediately to avoid further transmissionand get a new chance to properly identify the Tok
34、en Holder.3.9 Halt StateThe Halt State is a state in which an initialized Node remains, when the Controlling Layer (or othermechanism) has specified that the Node should not be participating on the IDB-C. In this state, the Node is aNot Present Node from the point of view of other Nodes.3.10 HDLCHig
35、h Level Data Link Control one of the protocols from which some features of the IDB-C Link Layerprotocol were adapted.3.11 IDB and IDB-CThe ITS Data Bus. This acronym describes a family of networks operating at different datarates and over different physical layers. This document describes the Link L
36、ayer protocol for the IDB-C, a lowspeed network based on CAN 2.0B.3.12 Insane NodeThis term is used to define a condition under which a Node is interfering with communicationon the network, and is not adhering to protocol specifications.3.13 ITS Intelligent Transportation Systems3.14 Key StateThe Ke
37、y State (Off, On, or Pulse) is implemented by the SAE J2590 PMODE specification. TheSAE J2366-2 Link Layer may need an out of band mechanism for querying or setting the Key State.3.14.1 KEY OFF STATEThe term “Key Off State” as used in this document has the same meaning as the PMODEOFF state as defin
38、ed in SAE J2590. In this state, the network operates in a manner that requires devices toconserve power, at the expense of some protocol efficiency.3.14.2 KEY ON STATEThe term “Key On State” as used in this document has the same meaning as the PMODEON state as defined in SAE J2590. The state is set
39、by the Vehicle Services Interface, typically based uponthe state of the vehicle key switch.The Key On State is the default state of the network in the absence of a Vehicle Services Interface providingpower mode information. This simplifies cabling and operation outside a vehicle.3.14.3 KEY PULSEThe
40、term “Key Pulse” is used in this document to describe the mechanism to wake up anetwork, as defined in SAE J2590. This signal activates the IDB-C while it is in the Key Off State. Onlydevices configured to operate in the Key Off State respond to a Key Pulse.3.15 LLC (Logical Link Control)This is a s
41、ub-layer of the Data Link Layer and forms the interface between theMAC and next higher layer in the protocol stack.3.16 MAC (Media Access Control)This sub-layer of the Data Link Layer (DLL) is responsible for control withinthe DLL. 3.17 NodeA Node is a device on the network. Each Node shall have at
42、least one physical Node ID. A Link Layeraddress of 0H is the logically lowest address and FH is the highest. The physical Node ID values are invertedwhen sent on the wire, both in the FromAddr and DestAddr header elements, as shown in Table 1, r =Recessive, d = Dominant.SAE J2366-2 Issued NOV2001-7-
43、3.17.1 ACTIVE NODEA Node is Active or in the Active state when it has a Node ID and is re-asserting its presenceperiodically, as defined in this document. An ACTIVE Node is fully participating in IDB-C activity.3.17.2 NOT ACTIVE NODEA Node is Not Active or is in the Not Active state when it has been
44、 assigned a Node ID,but fails (in the Key On State) to transmit any message within TInactive. After two consecutive such TInactiveperiods have elapsed, the Node is considered a Not Present Node. In the Key Off State, a Node does notbecome a Not Present Node for this reason.3.17.3 NOT PRESENT NODEA N
45、ode is said to be Not Present when it is not connected to the network, otherwisehas no Node ID, or has not transmitted any messages on the network within two TInactive periods. A Nodethat is Not Present may be in this state because it has chosen to leave the IDB-C, because it has justdetected power
46、applied to the network interface, or for other reasons. A Node may choose to leave thenetwork at any time.3.17.4 QUIESCENT NODEA Quiescent Node is a Node that is designed to operate in the Key Off State. In a networkall Nodes transition to Quiescent state or Not Active state simultaneously, based up
47、on the transition to theKey Off State. A Quiescent Node retains its Node ID and node map even after it stops actively transmittingon the network. A Quiescent Node becomes Active, retaining its Node ID, upon receipt of a Key Pulseindication.3.18 OctetAn octet is a unit of data transmission that consi
48、sts of eight bits. On most commonly usedmicroprocessors, such an eight-bit quantity is commonly referred to as a “byte”. The bits within an octet may besubdivided and/or grouped, to provide specific meanings.3.19 OSIOfficially known as the “ISO Reference Model of Open System Interconnection”. It ref
49、ers to a model, orway of thinking about communication protocols as being divided into (usually) seven distinct layers.3.20 PDU (Protocol Data Unit)Message packets exchanged between two protocol entities.3.21 Power Mode StateJ2366-1 and J2590 define a signal, PMODE, which indicates the power mode status ofthe IDB-C. This line indicates a PMODE bus state of ON (also called “Key On” in this document) or it indicatesa PMODE bus state of OFF (also called “Key Off” in this document). When pulsed to the Key On state, this lineindi
