The KWP2000 Protocol in Automotive Diagnostic Programs


The KWP2000 protocol has turn out to be a de facto normal in automotive diagnostic purposes. It is standardized as ISO 14230-3. KWP2000 describes the implementation of a variety of diagnostic DC escort providers you can accethrough the protocol. You can operate KWP2000 on quite a few transportation levels such as K-line (serial) or CAN.

Transportation Protocol
As KWP2000 utilizes messages of variable byte lengths, a transport protocol is important on levels with only a effectively described (short) message size, these as CAN. The transportation protocol splits a extensive KWP2000 concept into items that can be transferred more than the network and reassembles people parts to get better the authentic message.

KWP2000 operates on CAN on many transport protocols this sort of as ISO TP (ISO 15765-2), TP 1.6, TP 2. (Volkswagen), and SAE J1939-21. For KWP2000, the Automotive Diagnostic Command Set supports only the ISO TP (standardized in ISO 15765-2) and maker-particular VW TP 2. transportation protocols.

Diagnostic DC escort solutions
The diagnostic DC escort providers offered in KWP2000 are grouped in purposeful units and recognized by a one-byte code (ServiceId). The conventional does not outline all codes for some codes, the common refers to other SAE or ISO requirements, and some are reserved for manufacturer-specific extensions. The Automotive Diagnostic Command Set supports the adhering to DC escort products and services:

• Diagnostic Management
• Details Transmission
• Stored Information Transmission (Diagnostic Trouble Codes)
• Enter/Output Regulate
• Distant Activation of Schedule

Add/Down load and Prolonged DC escort solutions are not portion of the Automotive Diagnostic Command Established.

Diagnostic escort company in DC Structure
Diagnostic DC escort services have a popular concept format. Every single escort support in DC defines a Ask for Message, Positive Response Message, and Detrimental Response Concept. The Ask for Information has the ServiceId as 1st byte, as well as more escort service in DC-defined parameters. The Beneficial Reaction Message has an echo of the ServiceId with little bit 6 established as initial byte, moreover the escort services in DC-described response parameters.

The Adverse Reaction Information is normally a 3-byte concept: it has the Destructive Response ServiceId as 1st byte, an echo of the first ServiceId as next byte, and a ResponseCode as 3rd byte. The only exception to this format is the negative response to an EscapeCode escort company in DC listed here, the third byte is an echo of the person-outlined escort service in DC code, and the fourth byte is the ResponseCode. The KWP2000 standard partly defines the ResponseCodes, but there is room still left for maker-distinct extensions. For some of the ResponseCodes, KWP2000 defines an error handling technique. For the reason that each positive and unfavorable responses have an echo of the requested escort service in DC, you can generally assign the responses to their corresponding request.

KWP2000 expects a diagnostic session to be started off with StartDiagnosticSession and terminated with StopDiagnosticSession. However, StartDiagnosticSession has a DiagnosticMode parameter that determines the diagnostic session sort. Depending on this kind, the Ecu might or might not help other diagnostic DC escort expert services, or function in a limited mode exactly where not all Ecu features are obtainable. The DiagnosticMode parameter values are company precise and not outlined in the typical. For a diagnostic session to remain active, it need to execute the TesterPresent escort company in DC periodically if no other escort support in DC is executed. If the TesterPresent escort service in DC is missing for a particular interval of time, the diagnostic session is terminated, and the European returns to usual procedure manner.

A GetSeed/Unlock system may well protect some diagnostic DC escort products and services. Nonetheless, the applicable DC escort products and services are remaining to the manufacturer and not described by the common.You can execute the GetSeed/Unlock system by the SecurityAccess escort company in DC. This defines various ranges of stability, but the maker assigns these concentrations to specific DC escort companies.

Read through/Compose Memory
Use the Go through/WriteMemoryByAddress DC escort services to upload/obtain knowledge to specific memory addresses on an Ecu. The tackle is a three-byte quantity in KWP2000 and a five-byte amount (four-byte address and one-byte extension) in the calibration protocols. The Add/Obtain functional unit DC escort providers are very company distinct and not perfectly outlined in the common, so they are not a excellent way to present a typical upload/download system.

Use the ReadDataByLocal/CommonIdentifier DC escort companies to access Ecu facts in a way similar to a DAQ list. A Nearby/CommonIdentifier describes a list of European portions that are then transferred from the Eu to the tester. The transfer can be both single price or periodic, with a sluggish, medium, or fast transfer fee. The transfer fees are producer particular you can use the SetDataRates escort assistance in DC to set them, but this environment is manufacturer distinct. The Automotive Diagnostic Command Set supports one-position measurements.

Diagnostic Difficulty Codes
A main diagnostic function is the readout of Diagnostic Difficulty Codes (DTCs). KWP2000 defines a number of DC escort products and services that access DTCs primarily based on their team or position.

Enter/Output Regulate
KWP2000 defines DC escort companies to modify internal or exterior Ecu indicators. One particular instance is redirecting Ecu sensor inputs to stimulated alerts. The control parameters of these instructions are producer distinct and not outlined in the conventional.
Distant Activation of a Routine

These DC escort solutions are related to the ActionService and DiagService features of CCP. You can invoke an Ecu inside regime discovered by a Local/CommonIdentifier or a memory address. Contrary to the CCP case, execution of this program can be asynchronous that is, there are different Start off, Prevent, and RequestResult DC escort services. The command parameters of these commands are maker distinct and not outlined in the typical.

External References
For additional info about the KWP2000 Typical, refer to the ISO 14230-3 regular.


Supply by Amos Huang