Definitions have changed to Section 3 and Abbreviations to Section 4. All other section numbers have changed accordingly. The objectives of the subcommittee are to develop information reports, recommended practices, and standards concerned with the requirements design and usage of devices which transmit electronic signals and control information among vehicle components.
The usage of these documents is not limited to truck and bus applications; other applications may be accommodated with immediate support being provided for construction and agricultural equipment, and stationary power systems. These documents are intended as a guide toward standard practice and are subject to change as to keep pace with experience and technical advances.
New parameters and parameter groups are reviewed and discussed by the Subcommittee on a regular basis. This document reflects all changes and additions approved and balloted through December The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user. SAE invites your written comments and suggestions.
No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE.
Table Of Contents 1. Applicable Documents SAE Publications ISO Publications Technical Requirements General Guidelines Signal Characterization Message Format Parameter Ranges Assignment of Ranges to new Parameters Adding Parameters to Parameter Groups Transmission Repetition Rates Update Rates Naming Convention For Engine Parameters Application Notes Parameter Definitions Parameter Group Definitions Scope - As described in the parent document, SAE J, there are a minimum of seven documents required to fully define a complete version of this network.
References - 2. Unless otherwise indicated, the latest issue of SAE publications shall apply. This layer contains management functions and generally useful mechanisms to support applications. General Guidelines - 5. Signal Characterization - It is the intent of the SAE J network to provide current data and signals from a source so that it may be used by other nodes.
It is recommended that the time between physical data acquisition of a signal and the transmission of the data should not exceed two times the repetition rate defined for the data.
Additional constraints may be defined for certain parameters see also 5. Message Format - The message format of SAE J uses the parameter group number as the label for a group of parameters. Each of the parameters within the group can be expressed in ASCII, as scaled data defined by the ranges described in 5. Alphanumeric data will be transmitted with the most significant byte first.
Other parameters consisting of 2 or more data bytes shall be transmitted least significant byte first. 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. 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.
ISO Latin 1 Character Set - Horizontal boldface characters are the single hexidecimal digit representing the lower nibble of the single byte code for the character. Vertical boldface characters are the single hexidecimal digit representing the upper nibble of the single byte code for the character. See Figure 1. Vehicle Application Layer - J through December - p. Parameter Ranges - Table 1 defines the ranges used to determine the validity of a transmitted signal.
Table 2 defines the ranges used to denote the state of a discrete parameter and Table 3 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 parametric data is not currently available due to some type of error in the sensor, sub-system, or module. 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.
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.
Range Name Transmitted Value Enabled on, active, etc. Command to enable 01 function turnon, etc. However, if the measured or calculated data has yielded a value that is valid yet exceeds the defined parameter range, the error indicator should not be used. The data should be transmitted using the appropriate minimum or maximum parameter value. This permits data consistency to be maintained as much as possible between parameters of a given type temperature, pressure, speed, etc.
Each SLOT is intended to provide a range and resolution suitable for most parameters within a given type. When necessary, a different scaling factor or offset can be used.
This will minimize the math required for any internal scaling and reduce the opportunity for misinterpreted values. Adding Parameters to Parameter Groups - Several of the Parameter Groups contain bytes that are not defined and may be replaced with new parameters as appropriate. If existing parameter group definitions do not permit the inclusion of a new parameter, a new parameter group may be defined.
Refer to SAE J for additional definitions and abbreviations for instructions for adding new parameters to parameter groups and for requesting new parameter group numbers. In general, parameters should be grouped into parameter groups as follows: By function Oil, Coolant, Fuel, etc. With similar update rates to minimize unnecessary overhead By common subsystem the device likely to measure and send data. Transmission Repetition Rates Update Rates - 5. The average rate should be the nominal value.
When this is the case, the reference to a specific update rate is not accurate because this time will change based on the speed of the engine. The primary goal is to minimize the latency associated with sampling, calculating, and transmitting the data without overburdening the network. There are many approaches to sampling the data to be converted and sent over the network. The two preferred approaches are: a Time-based sampling, calculating, and transmission; and b A hybrid time-based and engine crank angle-based sampling, calculating, and transmission where the number of crank angle degrees between updates is modified based on the current operating speed in order to maintain an update rate within an acceptable range see Figure 2.
Because there are multiple ways to acquire and transmit data onto the network, the following guidelines have been defined for the engine speed and directly associated data. At speeds above rpm, the time from sampling to message transmission shall not exceed 12 ms. Systems that acquire engine speed information via period measurement inherently have less time delay at higher speeds.
Above rpm, for instance, the time from sampling to message transmission shall range from 5 to 30 ms. Less time is required because the period measurement takes less time at higher speeds. How much time is saved depends on the number of crank angle degrees used to perform the period measurement.
Normal update rates: Time based updates will occur every 20 ms. Hybrid time based and engine crank angle based updates are shown in Figure 2. Naming Convention For Engine Parameters - When there are multiple instances of the same parameter on the same component i. While facing the engine from the flywheel housing, left bank LB parameters are assigned prior to the right bank RB parameters.
For a six-cylinder in-line engine, the position furthest from the flywheel will be identified as 1. For a 12 cylinder V engine, the position furthest from the flywheel on the left bank will be identified as 1, followed by the position next closest to the flywheel on the left bank. When only one parameter is required or available, the parameter denoted as number 1 should be used. Application Notes - 5.
Parameters with Multiple Sources - Each parameter received by a node for control purposes shall be configurable by the system integrator to identify the primary source of the data, as well as the secondary source, if applicable. It is to be expected that the system integrator configure each receiving device on a network identically. The description includes data length, data type, resolution, range, and a tag label for reference. 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.
NOTE - A value of 0 indicates continuous real time pressure readings. Data Length: 1 byte Resolution: 0. In general the switch actuated by the operator's park brake control, whether a pedal, lever or other control mechanism.
Data Length: 2 bytes Resolution: 0. This parameter is intended for the primary accelerator control in an application. If an application has only one accelerator control, use SPN For on-highway vehicles, this will typically be the operator's accelerator pedal. Although it is used as an input to determine powertrain demand, it also provides anticipatory information to transmission and ASR algorithms about driver actions.
In marine applications, this will typically be the operator's throttle lever. See also SPNs for alternate range and resolution. If there is one boost pressure to report and this range and resolution is adequate, this parameter should be used.
This is the measurement of the first filter in a multiple air filter system. In a single air filter application, this is the only SPN used. Typical monitoring location is in the coolant expansion tank. Although the figure does not show rail 2 it does show the relationship of rail pressure to other signals. Flow rate of fresh air conducted to the engine cylinders to support combustion. Not to be used in place of defined parameters.
Data Range: 0 to 32, When a torque converter is present, it is the output of the torque converter. Data Range: 0 to 8, Characters may include P, Rx, Rx R2, R1, R, Nx, Nx If the first character is a control character, refer to the manufacturer's application document for definition. Resolution: 0. See SPNs and for engines with more than one exhause gas temperature measurement. Data Length: 4 bytes Resolution: 0.
This parameter is point 1 of the engine configuration map see PGN Note that the engine speed at point 2 SPN is equal to rated engine speed only in the case when the engine has not been derated. Please also reference PGN Data Range: 0 to ,, Not to be used in place of existing SPNs.
Dynamic commands from internal powertrain functions such as smoke control, low- and high-speed engine governing; ASR and shift control are excluded from this calculation. The data is transmitted in indicated torque as a percent of the reference engine torque. See PGN for the engine configuration message. Several status bits are defined separately to indicate the request which is currently being honored.
This parameter may be used for shift scheduling. The data is transmitted in indicated torque as a percent of reference engine torque see the engine configuration message, PGN The engine percent torque value will not be less than zero and it includes the torque developed in the cylinders required to overcome friction. It contains the frictional and thermodynamic loss of the engine itself, and the losses of fuel, oil and cooling pumps. The realization can be done by a map dependent on engine speed and engine temperature and an offset value for additional loss torques.
See SPN for an indicator that describes the possible inclusion of engine parasitic losses such as cooling fan, etc. These conditions may include the torque generated to accommodate powertrain demands from the operator via the accelerator pedal , cruise control, road speed limit governors, or ASR.
Dynamic commands from functions such as smoke control or shift control are excluded from this calculation. Data Range: 0 to Requested torque to the engine is measured in indicated torque as a percentage of reference engine torque see the engine configuration message, PGN This is the engine torque at which the engine is expected to operate if the torque control mode is active or the engine torque which the engine is not expected to exceed if the torque limit mode is active.
Requested torque to the retarder is measured in indicated torque as a percentage of reference retarder torque see the retarder configuration message, PGN The logic used in enabling or disabling the retarder is based on the override control mode priority bits SPN A zero torque request to the retarder is a disable request, and is used by a J node to prevent the retarder from being activated by other combinations of inputs outside of J commands.
The Torque Limit Mode is commonly used for this purpose. This is a scaled ratio such that represents an equal preference for a speed lower or higher that the engine's indicated desired speed. The higher the asymmetry adjustment value is above , the more the engine prefers to be operated at or above its indicated desired speed.
Conversely, the lower the asymmetry adjustment value is below , the more the engine prefers to operate at or below its indicated desired speed. The engine may include other factors into its asymmetry adjustment calculation such as temperatures, pressures, and other operating parameters. Used for electric brake applications. Transitions toward a destination gear will not be indicated. Once the selected gear has been engaged then Current Gear will reflect that gear.
Negative values are reverse gears, positive values are forward gears, zero is neutral, parameter specific indicators are listed below. It is possible that the shift selector software may not know the number of forward ranges. The shift selector may identify the position selected by the operator while the transmission ECU determines what range or gear that represents.
For example: Consider a vehicle with a 5-speed automatic transmission with the shift lever on the column. Suppose that shift selector has a limited number of positions, such that having positions for D is not an option.
For this example, assume there are only have enough lever positions for D Pulling the lever into "D" will put the transmission in 5th highest gear. It is desired that pulling the lever to the physical '3' position will limit the transmission to a maximum range of 3rd gear. When the selector is pulled down into "3", the shifter selector itself has no way of correlating this physical lever position to the desired gear; it would have to be calibrated with software to tell it this information.
If not calibrated, the shift selector cannot directly command the transmission to go to 3rd gear; it only knows it's one notch below drive. However, if "D-1" lever position, as opposed to desired gear is broadcast by the selector, the transmission ECU can receive this and then make the determination of what range is desired.
The benefit is that no specific calibration of the shift selector is required. Between selector positions 0xEE to 0xE2 - Indicates the shift selector is not in an appropriate position. If a lever-type shift selector with a mechanical display is stuck between detents, it may appear to the operator that it is in the desired position when in fact it is not. The shift selector may be capable of reporting only that it is between positions or that it is between forward or reverse positions.
If known, the transmission ECU may respond differently depending on which positions are involved. Reselect current position 0xE1 - If the TC1 message continues to send the position last selected, then a capability to reselect the same position is required. This indicator could also be sent between button presses as an alternative to sending the last button press. This is a status parameter. Reference: PGN 65, This parameter is used to indicate the current state, or mode, of operation by the cruise control device.
In engine configuration mode 1 and 3, point 2 is defined as the kick-in point from which torque is reduced to zero. It is recommended that one of these points indicate the peak torque point for the current engine torque map. Points 3, 4, and 5 are optional and lie between idle and point 2. This duration of the override is limited by the maximum momentary override time limit, SPN This parameter may be influenced by engine temperature after power up and other stationary changes calibration offsets, sensor failures, etc.
See also SPN In mode 2, there are no special requirements for the definition of this point. It is required that one of these points indicate the peak torque point for the current engine torque map. Points 3, 4, and 5 lie between idle and point 2. It is only defined once and doesn't change if a different engine torque map becomes valid. The factor is necessary for realizing flat curves with sufficient resolution as well as very steep curves. Please reference PGN The data is transmitted in indicated torque as a percent of the reference retarder torque.
It is only defined once and doesn't change if a different retarder torque map becomes valid. The low idle switch is defined in SAE J The kickdown switch is defined in SAE J This parameter should be used in conjunction with the parameter 'shift in Process' SPN While a shift is in process, the receiver should not assume that the driveline is either fully engaged or disengaged i.
Active means that ASR actually tries to control the engine. This state signal is independent of other control commands to the engine e. Active means that ASR actually controls wheel brake pressure at one or more wheels of the driven axle s. The signal is set active when wheel brake pressure actually starts to be modulated by ABS and is reset to passive when all wheels are in a stable condition for a certain time.
The signal can also be set active when driven wheels are in high slip e. Whenever the ABS system is not fully operational due to a defect or during off-road ABS operation , this signal is only valid for that part of the system that is still working.
When ABS is switched off completely, the flag is set to passive regardless of the current wheel slip conditions. The retarder does not check this switch, nor does the enabling of this switch engage the retarder. When this switch is 'enabled,' the devices constructing TSC1 ' destination retarder messages may command retarder torque for braking.
For example, the cruise control should not request retarder torque if this switch is not 'enabled. When this switch is 'enabled,' the transmission may activate the retarder via the TSC1 message to increase the rate of engine deceleration to assist in shift control.
The switch exists to prevent the engine retarder from being asked to be engaged via TSC1 in a noise sensitive area. See SPN This includes any transmission clutch control, all engine control sequences, pulling to transmission neutral, and engaging the destination gear e. While the driver alert mode is active, the idle shutdown timer may be overridden. It is not ensured that the engine is controlled by cruise control, as in the case of a large driver's demand the engine is controlled by the driver while cruise control is active maximum selection of cruise control and driver's demand.
The cruise control is set to 0 if a switch off condition occurs. This brake foot pedal is controlling the vehicles' service brake total vehicle braking application, not park brakes. It is necessary for safe drivetrain behavior that the switch activates before the physical braking components are activated i.
Disengage the cruise control function prior to the activation of friction brakes. It is necessary for a safe drivetrain behavior that the clutch switch is set before the clutch is opened cruise control function. When the switch is enabled, the pressure inside the circuit is too high and the compressor clutch may be disengaged. The maximum time for overspeed is limited by the time defined in the engine configuration message see PGN 65, The transmission module must command a 'override disabled' state at least once before the engine will accept a subsequent request for overspeed.
The speed limit governor is a droop governor where the speed limit value defines the speed at the maximum torque available during this operation. If a device wants to know whether it has access to the engine, there are several possibilities: a. Comparing its command with the actual engine broadcasts.
Looking at command modes from other devices. Looking to the engine and retarder torque mode. Remarks: a. The realization of a torque limit minimum selection is possible by setting the speed limit to a high value 0xFAFF. The realization of a speed limit minimum selection is possible by setting the torque limit to a high value 0xFA. Limiting the retarder torque means to limit the magnitude of the torque request. As the brake torque is represented by negative torque values, the limitation must be done by a maximum selection of the requested torque and the retarder internal torque signals.
For torque increasing functions, time limits for the torque or speed value command and the direct modes are desirable. The selection of which device has control of the engine's speed or torque depends on the override mode priority see SPN with the highest priority device gaining control.
The torque limit will be a 'lowest wins' selection e. RPM overshoot and undershoot may be greater than what is seen when the 'speed control characteristic' is set to be stability optimized. This gain adjustment is not intended to compensate for driveline characteristics. This characteristic is most appropriate when no driveline is connected.
For instance, the more complex plant would contain the engine, its accessory loads and the driveline characteristics. As an example, the driveline characteristics might include the effective spring mass relationship of pumps, tires, clutches, axles, driveshafts, and multiple gear ratios. This characteristic is most appropriate when a driveline is engaged.
It has been optimized to minimize rpm overshoot and undershoot given a more complex plant of the second variety. This more complex plant would again contain the engine, its accessory loads and a second driveline characteristic unique from the one described in speed control characteristic 10b. When the switch is enabled, the pressure inside the circuit is too low and the compressor clutch may be disengaged.
The default is 11 Low priority. It is not required to use the same priority during the entire override function. For example, the transmission can use priority 01 High priority during a shift, but can set the priority to 11 Low priority at the end of the shift to allow traction control to also interact with the torque limit of the engine.
This level of priority should only be used in safety critical conditions. An example is when the transmission is performing a shift and requires control of the engine in order to control driveline reengagement.
An example is when the traction control system is commanding the engine in order to achieve traction stability. An example is cruise control or the non-critical part of a transmission shift to a new gear. This is the engine speed which the engine is expected to operate at if the speed control mode is active or the engine speed which the engine is not expected to exceed if the speed limit mode is active.
Note that the modes are not in prioritized order. Not all modes may be relevant for a given device. Some devices may not implement all functions. The data type of this parameter is measured. The wheel brakes used in the vehicle are not designed for continuous retarding operation. In a prolonged period of braking, the brakes can be thermally over-stressed, causing the braking effect to be reduced or even lead to complete braking system failure.
The vehicle retarder is designed for continuous operation for braking during downhill operation and is also used for braking the vehicle to comply with speed limits and traffic conditions. This parameter provides some indication of the retarder dynamics.
It is used in the retarder configuration message See PGN A negative distance is transmitted if the service inspection has been passed. The component that requires service is identified by the service component identification see SPN , , and A negative value is transmitted if the service inspection has been passed.
The low order 4 bits represent a position number, counting left to right when facing in the direction of normal vehicle travel forward.
The high order 4 bits represent a position number, counting front to back on the vehicle. The value 0xFF indicates not available. It is recommended that output devices add 1 to the position number range 1 to 15, not 0 to 14 for use by drivers and service technicians.
Examples: Tire pressure for location 0x00 would be left front tire. Save money while getting up-to-date access to the standards you need!
Subscribe to the SAE J Standards Collection on the Web and get one year of anytime access and automatic updates to the J family of documents, plus all cross-referenced and selected related documents. Preview Document Add to Cart. Login to see discount. Special Offer: JPaks offers a customized subscription plan that is cost-effective and allows you to choose the number of downloads and Ground Vehicle documents you need. Find more information here. Get Involved Want to participate in updating this standard?
0コメント