KWP2000 protocol in automatic diagnostic equipment

The KWP2000 protocol has become a reality standard in automotive technology. It is standardized as ISO 14230-3. KWP2000 describes the implementation of various diagnostic tools that you can follow protocols. You can run KWP2000 on several transport modes like K-line (serial number) or CAN.

Transport Agreement
Because KWP2000 uses variable-length messages, it is necessary to transfer protocols to songs with only a well-defined (short) message length, such as CAN. The Exchange Agreement separates a long KWP2000 message that can be transferred over the Internet and combines those pieces to restore the original message.

KWP2000 runs CAN on various protocols such as ISO TP (ISO 15765-2), TP 1.6, TP 2.0 (Volkswagen) and SAE J1939-21. For KWP2000, the Automotive Diagnostic Command Set only supports ISO TP (Standard in ISO 15765-2) and manufactures special VW TP 2.0 protocols.

Diagnostic Services
The analyzers available in KWP2000 are classified into functional units and identified by a byte byte (ServiceId). The standard does not define all codes; For some codes, the standard is referred to other SAE or ISO standards, and some are reserved for manufacturer specific additions. Automatic Management System
• Data Transfer

Download / Download and Extended Services are not part of the Auto Admin.

Diagnostic Service Format
Diagnostic Services have a common message format. Each service defines a request for a message, a positive reply letter and a negative reply letter. The request for the message has ServiceId as the first byte, as well as additional service parameters. The positive response message has an echo of ServiceId with bit 6 as the first byte, plus service-responsive response changes.

The negative response message is usually a three-byte message: it has the negative response as the first byte, echo of the original ServiceId as the second byte and ResponseCode as the third byte. The only exception in this format is a negative response to EscapeCode services; here is the third byte of echo of the user-defined service code and the fourth byte is the answer code. The KWP2000 standard partially defines ResponseCodes, but it is the remaining space of the manufacturer-specific add-ons. For some response codes, KWP2000 defines the method of treatment treatment. Because both positive and negative feedback has an echo of the requested service, you can always associate the answers with the corresponding request.

Connect / Disconnect
KWP2000 assume that the diagnostic time begins with StartDiagnosticSession and discontinue StopDiagnosticSession. However, StartDiagnosticSession has DiagnosticMode variable that determines type of type analysis. Because of this type, the drive may or may not support other diagnostic technology or operate in closed mode because all operations in the ECU can not be obtained. DiagnosticMode variable values ​​are manufacturer specific and not defined in the standard. In order for the analysis time to be activated, it must perform the TesterPresent service on a regular basis if no other service is performed. If the TesterPresent service is missing for a specified period, the diagnostic period is closed and the ECU returns to normal operating mode.

GetSeed / Unlock
A GetSeed / Unlock mechanism can protect several diagnostics. However, the relevant services are left by the manufacturer and are not defined by standardization. You can run the GetSeed / Unlock system through the SecurityAccess service. This defines some levels of security, but the manufacturer allocates these limits to certain services.

Read / Write Memory
Use the Read / WriteMemoryByAddress service to download / download data to a particular memory number on ECU. The address is a three-bit amount in KWP2000 and a five-bit amount (four-byte address and one-sided addition) in the calibration charts. Upgrade / Charging the Functional Unit Service are highly selective and not well defined in the standard, so they are not a good way to provide a general setup / download system.

Measurements
Use the ReadDataByLocal / CommonIdentifier service to access authentic data in the same way as DAQ list. Local / CommonIdentifier describes a list of ECU quantities that are then transferred from ECU to the testing body. The transport can be either simple or regular, with slow, medium or speed. Carriage speed is a manufacturer specific; You can use the SetDataRates service to set them, but this setting is manufacturer specific. The Automotive Diagnostic Command Set supports single-point tracking.

Diagnostic Code
An extensive analysis method is read from the diagnostic code (DTCs). KWP2000 defines some services that access the DTC based on the group or their status.

Input / Output Control
KWP2000 defines a service for changing internal or external ECU signals. One example is to direct ECU sensor input to stimulate signal. Control parameters of these commands are manufacturer specific and not defined in the standard.
Remote Activation Routine

This service is similar to ActionService and DiagService features CCP. You can enter an internal routine in ECU that is defined by local / CommonIdentifier or lower address. In contrast to the CCP case, the implementation of this routine can be asynchronous; that is, there are separate Start, Stop and RequestResult services. Control parameters of these commands are manufacturer specific and not defined in the standard.

External References
Further information on the KWP2000 standard can be found in the ISO 14230-3 standard.

Source by Amos Huang

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