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CANdo OBD
Almost all cars manufactured since 2008 use a CAN bus for internal communication between the different ECUs & peripheral equipment, such as sensors & gauges.
An OBD (On Board Diagnostic) connector is fitted within easy reach of the steering wheel & provides access to the CAN bus for diagnostic purposes.
The CANdo Interface may be connected to this OBD connector via the CANdo OBD Cable to read diagnostic data.
The OBD connector is typically located below the steering wheel, on the underside of the dashboard, or in the centre console beneath a small cover.
The physical CAN bus on the connector complies with the ISO 11898-2 standard & so is compatible with the CANdo, CANdoISO & CANdo AUTO devices.
The raw CAN messages may be viewed & analysed using the CANdo Application software. The CAN messages themselves are formatted according to the
ISO 15765 standard. This standard specifies a CAN baud rate of either 250k or 500k baud, with 500k being the default.
A CANdo OBD cable is required to connect the CANdo Interface to the OBD connector in the vehicle. The CANdo OBD Cable is available to purchase from the online 'Store'.
CANdo
OBD
Software
The CANdo OBD software is designed to retrieve & display real time diagnostic data, fault codes & vehicle information from the vehicle's ECUs.
The software implements the ISO 15765 standard for 'Diagnostics Over CAN Bus' to communicate with the vehicle. The encoding of the parameter
requests & replies are in accordance with the ISO 15031 (SAE J1979) standard for 'Diagnostic Services'.
The CANdo OBD software is provided as one of the CANdo Demonstration programs & is available as a FREE download from the 'Download' page.
The software is written in Visual C# & is based on the CANdo SDK. Full source code is provided within the CANdo Demonstrations download.
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Current Data - Service $01
The Current Data mode, requests a number of common engine & vehicle parameters in real time & displays the current values in a list.
The parameters displayed are stored within in a table in the source code & are fairly easy to change, if armed with a copy
of the ISO 15031 or SAE J1979 specification & Visual Studio C# Express.
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Freeze Frame - Service $02
The Freeze Frame mode, displays the frozen parameter values captured & stored within the ECU as a result of one or more detected faults.
The fault code relating to the detected fault that prompted the freeze frame capture is displayed on the first line.
If no faults are present & there is no freeze frame data, then all the values are displayed as blanks.
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Fault Codes - Services $03 & $04
If the MIL (Malfunction Indicator Lamp) is illuminated on the vehicle dashboard, then the Fault Codes mode will read & display the current reported diagnostic trouble codes.
If the file 'DTCs.txt' is present in the same directory as the CANdo OBD executable, then a text description of the fault code is also displayed, if the DTC is found
within the file.
If one or more faults are present, then the Fault Codes button is replaced with a Clear Faults button. This button allows the fault codes stored within the ECU to be cleared.
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Vehicle Info. - Service $09
The Vehicle Info. mode, displays a few parameters that identify the vehicle & the ECU.
In this mode the program decodes multi-frame CAN messages in accordance with the ISO 15765-2 standard to retrieve the values.
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Notes :
- The CANdo OBD software is available as a FREE download from the 'Download' page
- Both the CANdo Interface & the CANdo OBD Cable are available to purchase from the online store
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