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==Introduction==
==Authorized Read Notification==
'''Important: ''iButton Read Notification'' feature has been replaced with ''Authorized Read Notification'' starting from Firmware Ver.03.30.00''' <br>
With a professional device lineup, telltale information (dashboard indicators) from heavy-duty vehicles can be read remotely to identify a variety of issues. New feature of Diagnostic Trouble Code (DTC) reading will help to narrow down the specific faults happening in vehicles.
Authorized read notification feature allows the control of selected DOUT for a configured period, when '''Authorized ID''' is read using '''1-Wire''', '''RFID Reader''' or when '''Authorized Beacon''' is detected. If Authorized ID List is empty or Beacon detection is set to '''All''', then any detected ID or Beacon can control selected DOUT. Parameter '''Depend on Ignition''' allows to disable DOUT control, while Ignition is being detected. It is necessary to select at least one source for this functionality to work.
With {{{model}}} you can read 2 types of DTC messages based on J1939 protocol:
Authorized Read Notification parameters:
*DM1 – Communicates currently present faults
*'''Output Control''' – available scenario settings for module Digital output activation/deactivation
*DM2 – Reports stored faults
*'''DOUT ON Duration''' – a value in seconds, for how long {{{text_dout|DOUT1/DOUT2}}} should be active or inactive.
*'''Authorization ID List Checking''' - Provides Authorized ID information from a designated source.
**FMB devices that do not have RS232 will have support for 1-Wire and Beacon only.
**FMB devices that do not have RS232 and 1-Wire will have support for Beacon only.
*'''Depend on Ignition''' - Output will be triggered only if ignition is off.
{{{model}}} is able to read DM codes and pass them to the server in IO element. When active DM1 or DM2 messages appear on CAN line it is broadcasted very often – {{{model}}} device saves the codes into the internal memory and does not flood the server with irrelevant information – only new DTC codes are sent to the server.
'''Note:''' Authorized read notification is disabled in '''deep sleep''', '''online deep sleep''' and '''ultra deep sleep''' modes.
==Functionality Description==
This functionality is available from Firmware version '''03.01.02.rev.06''' or higher.
For proper functionality, the device requires ignition to be active. Source of ignition and voltage level can be selected from '''System''' tab.
Ignition has to be active for at least 14 sec to start generating the DTC list. If ignition is turned off, the device will clean all DM1 and DM2 codes and functionality will not be working.
[[File:DTC_Ignition.png]]
After the device is connected to the Configurator, there will be '''DM1 / DM2''' tab made available. There is a configurable DM1 / DM2 Data source parameter. This parameter selects the CAN source based on which device will parse DM data from. Based on selected data source, device will also call a request for DTCs.
'''Note:''' The functionality is completely separated from the FMS source.
[[File:DTC Data source selection.png]]
*NONE – Device will not use any CAN as data source
*CAN1 – Device will use CAN1 as data source
*CAN2 – Device will use CAN2 as data source
*BOTH – Device will use CAN1 and CAN2 as data source
Bellow '''Data source''' parameters there is a list of configurable IOs
[[File:DTC Configurable IOs.png]]
„DTC DM1“ and “DTC DM2“ shows the last DTC that has been detected. „Active DM1 List“ and „Active DM2 List“ provides a list of all active DTCs for a given source.
Example of generating DM1 / DM2 list: To register DM1 code, it is required to send a command using (pgn 0xFEFA). Device will first check if such DTC code exist in the system (MCUID and CAN Source has to be unique for each DTC). Otherwise, DTC will be rejected.
*<span style="color:green;">9D000302</span> – DTC in hexadecimal format
*<span style="color:blue;">02</span> – MCU source that reported the DTC
*<span style="color:red;">01</span> – Device CAN source used (00 - CAN1, 01 - CAN2)
Based on configured „Priority“, „Event Only“ and „Operand“ device will add this parameter to record.
[[File:DTC Terminal logs.png]]
To remove one of the DTC from DM1 list, DM2 code (pgn 0xFEFB) is required. Device will check if the sent DTC code exists in the system (MCUID and CAN Source has to be unique for each DTC). If sent DTC does not exist in the system, it will be rejected.
Based on previous example, sending DTC 9D000301 with MCUID 01 on CAN2, device remove this DTC from the system, as the result, this DTC is removed from „Active DM1 List“ and added to the „Active DM2 List“.
[[File:DTC Configurator outputs 2.png]]
Log example:
[[File:DTC Terminal logs 2.png]]
That DTCs will be added to record and would be accessible on server. Data on server need to be converted from HEX to ASCII.
[[File:DTC Outputs from server.png]]
'''39443030303330323A30323A30313B''' -> (after conversion from hex to ANSCII) '''9D000302:02:01''';
'''39443030303330313A30313A30313B''' -> (after conversion from hex to ANSCII) '''9D000301:01:01''';
==Functionality Block Diagram==
Graphic representation of '''DM1''' and '''DM2''' functionality:
[[File:DTC Functionality blok diagram.png]]
==DM1 Lamp Status and Flash Signals==
The '''DM1 (Diagnostic Message 1)''' in the '''J1939''' protocol reports active '''Diagnostic Trouble Codes (DTCs)''' and controls vehicle warning indicators. It defines the behavior of the '''Malfunction Indicator Lamp (MIL)''' and other warning lamps, which can be off, on solid, or flashing, depending on the severity and priority of detected faults. Flashing typically signals a more urgent or severe condition, while a solid light indicates an active but less critical issue.
The first byte represents the status of four indicator lamps:
*'''AWL(Amber Warning Light)''' - DTC's indicate a non-critical issue that does not warrant stopping the vehicle.
*'''RSL(Red Stop Lamp)''' - DTC's indicate a critical issue that warrants stopping the vehicle immediately.
*'''MIL(Malfunction Indicator Lamp)''' - At least one DTC indicates emissions related issue.
Each lamp is encoded using 2 bits, allowing four possible states: '''off, on, slow flash, and fast flash'''. This compact encoding means all lamp states are conveyed within a single byte, with each pair of bits mapped to a specific lamp in a fixed order. These lamp states directly inform the operator about the severity and urgency of active faults.
DM1 encodes warning lamp information in its first 2 bytes, combining both lamp status and flash behavior. Each lamp is represented by two 2-bit fields—one in byte 1 (status) and one in byte 2 (flash).
To decode, split each byte into 2-bit segments and map each pair to its corresponding lamp. The final behavior is determined by combining status and flash (e.g., ON + fast flash = rapidly blinking warning).
==Global and Manufacturer SPN Codes==
===Global-Level SPN codes===
Standard codes are defined by the SAE J1939 standards and are recognized across all compliant vehicles and equipment. The SPNs for these codes fall within the range of '''1 to 24,324''' representing widely used parameters such as engine speed, coolant temperature, or oil pressure. FMI values are standardized, describing specific failure patterns such as high voltage, circuit open, or out-of-range conditions.
Because they are standardized, these codes are universally interpretable by any compliant diagnostic tool without requiring manufacturer-specific references.
===Manufacturer-Level SPN codes===
Manufacturer-level or proprietary codes are reserved for OEM-specific faults that are not defined in the J1939 standard. These allow manufacturers to monitor unique components, systems, or operational conditions that are specific to their equipment.
The SPNs for proprietary codes typically occupy the high end of the 19-bit field, ranging from '''516,096 to 524,287'''. FMI values may be standard or custom, but the meaning of the SPN is defined by the manufacturer. Accurate interpretation requires access to OEM documentation, as these codes are not universally defined or interpretable.
==DM1/DM2 Message Structure==
'''DM1''' is a J1939 diagnostic message used to broadcast active faults and warning lamp status. Its structure is split into a header (lamp status) followed by one or more diagnostic trouble codes. Unlike most J1939 messages, DM1 has a variable length: if there are 0–1 active DTCs, it fits in a single CAN frame, while 2 or more DTCs require a multi-frame message with additional DTC entries added.
[[File:DM1,DM2 Message Structure.png]]
The first 2 bytes form the lamp status header, which is shared across all DTCs. Each lamp uses 2-bit values to indicate status (off/on), along with flash signals defining how the lamp blinks (slow or fast). These signals are interpreted collectively across ECUs, with a central controller typically deciding the final lamp behavior based on the most severe reported condition.
Each DTC contains four key components:
*'''SPN(''Suspect Parameter Number)''''' - Identifies the faulty subsystem.
*'''FMI(''Failure Mode Identifier)''''' - Describes the type of failure.
*'''CM(''SPN Conversion Method)''''' - Indicates the encoding method.
*'''OC(''Occurrence Count)''''' - Counts how often the fault has occurred.
These elements provide detailed, structured information about vehicle faults while supporting both standardized and proprietary diagnostics.
Revision as of 12:44, 3 April 2026
Authorized Read Notification
Important: iButton Read Notification feature has been replaced with Authorized Read Notification starting from Firmware Ver.03.30.00
Authorized read notification feature allows the control of selected DOUT for a configured period, when Authorized ID is read using 1-Wire, RFID Reader or when Authorized Beacon is detected. If Authorized ID List is empty or Beacon detection is set to All, then any detected ID or Beacon can control selected DOUT. Parameter Depend on Ignition allows to disable DOUT control, while Ignition is being detected. It is necessary to select at least one source for this functionality to work.
Authorized Read Notification parameters:
Output Control – available scenario settings for module Digital output activation/deactivation
DOUT ON Duration – a value in seconds, for how long DOUT1/DOUT2 should be active or inactive.
Authorization ID List Checking - Provides Authorized ID information from a designated source.
FMB devices that do not have RS232 will have support for 1-Wire and Beacon only.
FMB devices that do not have RS232 and 1-Wire will have support for Beacon only.
Depend on Ignition - Output will be triggered only if ignition is off.
Note: Authorized read notification is disabled in deep sleep, online deep sleep and ultra deep sleep modes.
