ISO 11992-3:1998

Road vehicles — Electrical connections between towing and towed vehicles — Interchange of digital information — Part 3: Application layer for non-braking equipment

Véhicules routiers — Connexions électriques entre véhicules tracteurs et véhicules tractés — Échange de données numériques — Partie 3: Couche application pour l'équipement autre que de freinage

General Information

• Status: Withdrawn
• Publication Date: 25-Mar-1998
• Withdrawal Date: 25-Mar-1998
• ICS: 43.040.10 - Electrical and electronic equipment
• ICS: 43.040.15 - Car informatics. On board computer systems
• Technical Committee: ISO/TC 22 - Road vehicles
• Drafting Committee: ISO/TC 22 - Road vehicles
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 30-Apr-2003

Relations

• Revised: ISO 11992-3:2003 - Road vehicles — Interchange of digital information on electrical connections between towing and towed vehicles — Part 3: Application layer for equipment other than brakes and running gear
• Effective Date: 15-Apr-2008
• Consolidated By: ISO 13295:2007 - Dentistry — Mandrels for rotary instruments
• Effective Date: 06-Jun-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 11992-3
First edition
1998-04-01
Road vehicles — Electrical connections
between towing and towed vehicles —
Interchange of digital information —
Part 3:
Application layer for non-braking equipment
Véhicules routiers — Connexions électriques entre véhicules tracteurs et
véhicules tractés — Échange de données numériques —
Partie 3: Couche application pour l'équipement autre que de freinage
A
Reference number
ISO 11992-3:1998(E)

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© ISO
ISO 11992-3:1998(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
International Standard ISO 11992-3 was prepared by Technical Committee ISO/TC 22, Road vehicles,
Subcommittee SC 3, Electrical and electronic equipment.
ISO 11992 consists of the following parts, under the general title Road vehicles — Electrical connections between
towing and towed vehicles — Interchange of digital information:
— Part 1: Physical layer and data link layer
— Part 2: Application layer for braking equipment
— Part 3: Application layer for non-braking equipment
Annex A of this part of ISO 11992 is for information only.
©  ISO 1998
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet [e-mail]
X.400 c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland
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© ISO
ISO 11992-3:1998(E)
Introduction
This part of ISO 11992 is subject to additions which will become necessary to keep pace with experience and
technical advances. Care has been taken to ensure that these additions can be introduced in a compatible way, and
care will have to be taken in the future that such additions remain compatible with previous versions. In particular, it
may become necessary to standardize new parameters and parameter groups. ISO members may request that
such new parameters and parameter groups be included in future editions of ISO 11992 by completing the
"Parameter identification form" in annex A and submitting it to ISO/TC 22/SC 3.
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INTERNATIONAL STANDARD  © ISO ISO 11992-3:1998(E)
Road vehicles — Electrical connections between towing and towed
vehicles — Interchange of digital information —
Part 3:
Application layer for non-braking equipment
1 Scope
This part of ISO 11992 specifies the data content for electronically controlled systems other than braking systems to
ensure the interchange of digital information between road vehicles of a maximum authorised total mass greater
than 3 500 kg, and their towed vehicles, including communication between towed vehicles.
The objective of the data structure is to achieve an optimised use of the interface, whilst preserving a sufficient
reserve capacity for future expansion.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this part of
ISO 11992. At the time of publication, the editions indicated were valid. All standards are subject to revision, and
parties to agreements based on this part of ISO 11992 are encouraged to investigate the possibility of applying the
most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid
International Standards.
ISO 11898:1993, Road vehicles — Interchange of digital information — Controller area network (CAN) for high
speed communication.
ISO 11992-1:1998, Road vehicles — Electrical connections between towing and towed vehicles — Interchange of
digital information — Part 1: Physical layer and data link layer.
ISO 11992-2:1998, Road vehicles — Electrical connections between towing and towed vehicles — Interchange of
digital information — Part 2: Application layer for braking equipment.
3 Definitions
For the purposes of this part of ISO 11992, the definitions given in ISO 11992-1 and ISO 11992-2 apply.
4 General specifications
The data link and the physical layer shall be in accordance with ISO 11992-1.
To minimise bus loading on the towing/towed vehicle interface appropriate messages are specified. These
messages may be filtered by a device (node) on each vehicle which shall also provide address assignment and
electrical isolation from the in-vehicle sub-network.
The architecture was chosen to permit a mix of new and old towing and towed vehicles in any combination. Multiple
towed vehicles can be connected in any combination; the network shall be capable of addressing any towed vehicle
(dolly). The truck operator can disconnect and connect towed vehicles at any time and any order and the network
shall adjust and respond accordingly.
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5 Application layer
5.1 Message frame format
The application layer provides a string of information that is assimilated into a protocol data unit (PDU). The PDU
provides a framework for organizing the information which will be sent by the CAN data frame.
This 29 bit identifier shall be in accordance to ISO 11898.
The PDU shall consist of seven fields additional to the specific CAN fields (see figure 1).
The PDU fields are Priority (P), Reserved (R), Data Page (DP), PDU Format (PF), PDU Specific (PS), which can be
a Destination Address (DA) or a Group Extension (GE), Source Address (SA) and data field.
P R DP PF PS SA Data field
3 1 1 8 8 8 0 to 64
Figure 1 — 29-bit CAN identifier
5.1.1 Priority
The three priority bits are used to optimise message latency for transmission onto the bus only. They should
globally masked off by the receiver (ignored). The priority of any message may be set from highest, 0 (000 ), to
2
lowest, 7 (111 ). The default for all control oriented messages is 3 (011 ). The default of all other informational
2 2
messages is 6 (110 ).
2
5.1.2 Reserved bit (R)
This bit is reserved for future expansion. This bit should be set to zero for transmitted messages.
5.1.3 Data page (DP)
The data page bit selects an auxiliary page of parameter group descriptions.
5.1.4 PDU format (PF)
The PDU format is an eight-bit field that determines the PDU format and is one of the fields used to determine the
parameter group number assigned to the data field. Parameter group numbers shall be used to identify or label a
set of commands and data.
5.1.5 PDU specific (PS)
The PDU specific is an eight-bit field and depends on the PDU format. Depending on the PDU format it can be a
destination address or a group extension. If the value of the PDU format (PF) field is below 240, the PDU specific
field is a destination address. If the value of the PF field is 240 to 255, then the PDU specific field contains a group
extension (GE) value (see table 1).
Table 1 — PDU specific field
PDU format PDU specific (PS)
(PF) field field
PDU 1 field 0 to 239 Destination address
PDU 2 field 240 to 255 Group extension
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5.1.5.1 Destination address (DA)
This field contains the specific address of the towing and towed vehicle to which the message is being sent. Any
other device shall ignore this message. The global destination address (255) requires all devices to listen.
5.1.5.2 Group extension (GE)
The group extension field, in conjunction with the four least significant bits of the PDU format field provide for 4 096
parameter groups per data page.
When the four most significant bits of the PDU format field are set it indicates that the PS field is a group extension.
5.1.6 Source address (SA)
The source address field is eight-bits long. There shall only be one device on the network with a given source
address. Therefore, the source address field assures that the CAN identifier will be unique, as required by CAN.
5.1.7 Data field
A single CAN data frame provides at maximum eight data bytes. Even if fewer than eight bytes are required for
expressing a given parameter group number, all eight bytes shall be used. This provides a means to easily add
parameters and not to be incompatible with previous revisions which only specified part of the data field.
5.1.8 Parameter group number (PGN)
The parameter group number is a 24-bit number which contains: Reserved bit, Data page bit, PDU Format field
(eight bits), and PDU specific field (eight bits) (see table 2).
If the PF value is less than 240 (F0H; PDU 1 type message) then the lower byte of the PGN is set to zero.
Table 2 — Content of the parameter group number
Byte 1 (MSB)
Byte 2 Byte 3
Bits 8.3 Bit 2 Bit 1
000000b Reserved Data Page PDU format PDU specific
5.1.9 PDU 1 format
The PDU format allows for applicable messages to be sent to either a specific or global destination. PDU 1 format
messages are determined by the PDU format (PF) field. When the PDU format field value is 0 to 239, the message
is a PDU 1 format.
5.1.10 PDU 2 format
The PDU 2 format may only be used to communicate global messages. PDU 2 format messages are those where
the PDU format (PF) field value is equal to 240 to 255.
5.2 Address assignment
A road train consists of one commercial vehicle and one or more towed vehicle(s). Dolly axles within the road train
are treated as towed vehicles as well (see figure 2).
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Figure 2 — Example of possible road train configuration
The address of the commercial vehicle is fixed.
The respective address of a towed vehicle corresponds to its position within the road train and has to be newly
assigned each time
 communication starts,
 a towed vehicle has been connected.
For towing vehicle/towed vehicle communication the addresses shown in table 3 shall be used as source addresses
(SA) and destination addresses (DA). To avoid any transmission conflict during the dynamic address assignment
phase (power-up), the PDU 2 type message shall have even PS (GE) in predecessor transmission direction and
odd PS (GE) in successor transmission direction. If the same message has to be sent in both transmission
directions, two PS (GE) are necessary.
Table 3 — Commercial vehicle/towed vehicle addresses
Name Address Predecessor Successor
Commercial vehicle 32d = 20h N/A Towed vehicle position #1
(position #0)
Towed vehicle position #1 200d = C8h Commercial vehicle Towed vehicle position #2
(position #0)
Towed vehicle position #2 192d = C0h Towed vehicle position #1 Towed vehicle position #3
Towed vehicle position #3 184d = B8h Towed vehicle position #2 Towed vehicle position #4
Towed vehicle position #4 176d = B0h Towed vehicle position #3 Towed vehicle position #5
Towed vehicle position #5 168d = A8h Towed vehicle position #4 undefined
Global destination address 255d = FFh undefined undefined
The dynamic address assignment shall be handled by the respective towing vehicle/towing vehicle node and
concerns the determination of the individual position within the road train. The global destination address shall be
only used by the commercial vehicle to broadcast information to all towed vehicles simultaneously.
The dynamic address assignment is based on the transmission of the standard initialization message (see 5.5) by
the respective predecessor within the road train.
Within a road train, the address assignment procedure shall be initiated by the commercial vehicle, using its
standard address for the standard initialization message (see table 3). A powered-up towed vehicle node shall use
the towed vehicle #1 address as the default address to transmit available information, until the standard initialization
has been received and a valid address can be assigned.
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This allows the towed vehicle node to communicate and to identify its presence to its predecessor immediately after
power-up. This could mean that several towed vehicles might use the same address, until the address assignment
procedure has been completed.
An assigned address shall be valid as long as the standard initialization message is received from the predecessor
with the corresponding source address and specified message timing.
To provide address assignment for itself and for possible successors, a node shall be capable of permanently
sending the standard initialization message with its own source address (see figure 3).
Permanent sending of the initialization message is necessary to allow immediate towed vehicle address assignment
at any time a towed vehicle might be connected.
In addition, a towed vehicle node shall be capable of
 identifying its predecessor by the source address of the standard initialization message;
 assigning its own address based on the predecessors address;
 identifying potential receiver(s) by the destination address and by the message type.
Towed Towed
Commercial SA = Com. Vehicle SA = Towed Vehicle #1 SA = Towed Vehicle #2
Vehicle Vehicle
Vehicle
>32d< #1 >200d< #2 >192d<
- sends SA = Commercial Vehicle to successor
- receives SA = Commercial Vehicle from predecessor
- claims SA = Towed Vehicle #1
- sends SA = Towed Vehicle #1 to successor
- receives SA = Towed Vehicle #1 from predecessor
- claims SA = Towed Vehicle #2
- sends SA = Towed Vehicle #2 to successor
Figure 3 — Address assignment
5.3 Message routing
To allow communication between towing and towed vehicles, a node shall be capable of
 receiving messages from its predecessor and successor within the road train;
 identifying receiver(s) by the destination address (PDU 1 type messages) or the PDU format (PDU 2 type
messages);
 routing all messages from its predecessor(s) to its successor(s) within the road train by sending them with the
1)
unchanged source and destination address to its successor within a maximum delay time of t = 13 ms;
d
 routing all messages from its successor(s) to its predecessor(s) within the road train by sending them with the
1)
unchanged source and destination address to its predecessor within a maximum delay time of t = 13 ms.
d

1)
If no provisions are provided for a successor, this function is not required.
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A towed vehicle node shall not route messages to its successor or predecessor within the road train, if the source
address of a message received from its
 predecessor corresponds to a road train position higher or equal to its own;
 successor corresponds to a road train position lower or equal to its own.
Figures 4 to 9 illustrate the PDU type message sent in different directions.
Towed Towed Towed
PF = xxx PF = xxx PF = xxx
Commercial
DA = Towed Vehicle #1 Vehicle DA = Towed Vehicle #2 Vehicle DA = Towed Vehicle #3 Vehicle
Vehicle
SA = Commercial Vehicle #1 SA = Towed Vehicle #1 #2 SA = Towed Vehicle #2 #3
Figure 4 — Example of PDU 1 type messages from towing vehicle to succeeding towing vehicle
PF = xxx Towed PF = xxx Towed Towed
Commercial
DA = Towed Vehicle #2 Vehicle DA = Towed Vehicle #2 Vehicle no transmission Vehicle
Vehicle
SA = Commercial Vehicle #1 SA = Commercial Vehicle #2 #3
Figure 5 — Example of PDU 1 type message from towing vehicle to towed vehicle #2
PF = xxx Towed PF = xxx Towed PF = xxx Towed
Commercial
DA = GE Vehicle DA = GE Vehicle DA = GE Vehicle
Vehicle
SA = Commercial Vehicle #1 SA = Commercial Vehicle #2 SA = Commercial Vehicle #3
Figure 6 — Example of PDU 2 type message from commercial vehicle to all towed vehicles
PF = xxx Towed PF = xxx Towed PF = xxx Towed
Commercial
DA = Commercial Vehicle Vehicle DA = Towed Vehicle #1 Vehicle DA = Towed Vehicle #2 Vehicle
Vehicle
SA = Towed Vehicle #1 #1 SA = Towed Vehicle #2 #2 SA = Towed Vehicle #3 #3
Figure 7 — Example of PDU 1 type messages from towed vehicle to preceding towing vehicle
PF = xxx Towed PF = xxx Towed PF = xxx Towed
Commercial
DA = Commercial Vehicle Vehicle DA = Commercial Vehicle Vehicle DA = Commercial Vehicle Vehicle
Vehicle
SA = Towed Vehicle #3 #1 SA = Towed Vehicle #3 #2 SA = Towed Vehicle #3 #3
Figure 8 — Example of PDU 1 type message from towed #3 to commercial vehicle
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PF = xxx Towed PF = xxx Towed PF = xxx Towed
Commercial
DA = GE Vehicle DA = GE Vehicle DA = GE Vehicle
Vehicle
SA = Towed Vehicle #2 #1 SA = Towed Vehicle #2 #2 SA = Towed Vehicle #2 #3
Figure 9 — Example of PDU 2 type message from towed vehicle #2
5.4 Parameters
5.4.1 Parameter ranges
Table 4 specifies the ranges used to determine the validity of transmitted signal.
Table 5 specifies the ranges used to denote the state of a discrete parameter and table 6 defines the ranges used
to denote the state of a control mode command.
The values in the range "error indicator" provide a means for a module to immediately indicate that valid parameter
data is not currently available due to some type of error in the sensor, sub-system, or module. Additional information
about the failure may be available using diagnostic requests.
The values in the range "not available" provide a means for a module to transmit a message which contains a
parameter that is not available or not supported in that module. This value does not replace the "error indicator".
The values in the range "not requested" provide a means for a device to transmit a command message and identify
those parameters where no response is expected from the receiving device.
Table 4 — Transmitted signal ranges
Value range
Parameter Unit
1 byte 2 bytes
Dec 0 to 250 0 to 64255
Signal range
Hex 00 to FA 0000 to FAFF
Dec 251 to 253 64256 to 65023
Reserved range for
future indicator bits
Hex FB to FD FB00 to FDFF
Dec 254 65024 to 65279
Error indicator
Hex FE FExx
Dec 255 65280 to 65535
Not available or
not requested
Hex FF FFxx
Table 5 — Transmitted values for discrete parameters
Range name Transmitted value
Disabled (off, passive, insufficient) 00
Enabled (on, active, sufficient) 01
Error indicator 10
Not available or not installed 11
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Table 6 — Transmitted values for control requests
Range name Transmitted value
Request to disable function (turn off, etc.) 00
Request to enable function (turn on, etc.) 01
Reserved 10
Don't care/take no action 11
(leave function as it is)
After power on, a node should internally set the "availability bits" of received parameters as not available and
operate with default values until valid data is received. When transmitting, undefined bytes should be sent as
255Dec (FFHex) and undefined bits should be sent as "1".
If a component failure prevents the transmission of valid data for a parameter, the error indicator, as described in
tables 4 and 5, shall be used in place of that parameter data. However, if the measured of calculated data has
yielded a value that is valid yet exceeds the defined parameter range, the error indicator shall not be used. The data
should be transmitted using the appropriate minimum or maximum parameter value.
A word (16 bit) parameter shall be sent, least significant byte first, most significant byte second.
5.4.2 Parameter specifications
5.4.2.1 General
A description of each parameter is given in 5.4.2.2 to 5.4.2.30. The description includes data length, data type,
resolution and range for reference.
The type of data shall also be identified for each parameter. Data may be either status or measured. Status
specifies the present state of a multi-state parameter or function as a result of action taken by the transmitting node.
Note that specific confirmation of this action is not necessarily assured. For instance, the status may indicate that a
solenoid has been activated, yet no measurement may have been taken to ensure the solenoid accomplished its
function. An example of status-type data is "lift axle position request".
Measured data conveys the current value of a parameter as measured or observed by the transmitting node to
determine the condition of the defined parameter. An example of measured-type data is "thermal body
temperature".
N
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