The KWP2000 Protocol in Automotive Diagnostic Purposes

The KWP2000 protocol has grow to be a de facto regular in automotive diagnostic applications. It is standardized as ISO 14230-3. KWP2000 describes the implementation of different diagnostic DC escort companies you can accethrough the protocol. You can run KWP2000 on a number of transportation levels this sort of as K-line (serial) or CAN.

Transport Protocol
As KWP2000 takes advantage of messages of variable byte lengths, a transport protocol is vital on layers with only a nicely described (limited) message duration, these kinds of as CAN. The transportation protocol splits a lengthy KWP2000 concept into pieces that can be transferred around the community and reassembles all those parts to get better the primary concept.

KWP2000 operates on CAN on numerous 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 Established supports only the ISO TP (standardized in ISO 15765-2) and company-distinct VW TP 2. transport protocols.

Diagnostic DC escort providers
The diagnostic DC escort solutions out there in KWP2000 are grouped in purposeful models and determined by a one particular-byte code (ServiceId). The conventional does not define all codes for some codes, the normal refers to other SAE or ISO standards, and some are reserved for company-specific extensions. The Automotive Diagnostic Command Established supports the subsequent DC escort expert services:

• Diagnostic Administration
• Information Transmission
• Stored Details Transmission (Diagnostic Difficulty Codes)
• Input/Output Management
• Remote Activation of Routine

Upload/Obtain and Prolonged DC escort companies are not portion of the Automotive Diagnostic Command Set.

Diagnostic escort support in DC Format
Diagnostic DC escort products and services have a widespread information structure. Each escort assistance in DC defines a Ask for Concept, Positive Reaction Message, and Damaging Reaction Message. The Request Information has the ServiceId as very first byte, furthermore supplemental escort provider in DC-described parameters. The Positive Response Concept has an echo of the ServiceId with bit 6 set as to start with byte, in addition the escort company in DC-defined reaction parameters.

The Negative Response Message is usually a a few-byte information: it has the Damaging Reaction ServiceId as very first byte, an echo of the original ServiceId as second byte, and a ResponseCode as third byte. The only exception to this format is the destructive response to an EscapeCode escort services in DC here, the 3rd byte is an echo of the user-described escort provider in DC code, and the fourth byte is the ResponseCode. The KWP2000 conventional partly defines the ResponseCodes, but there is space left for manufacturer-precise extensions. For some of the ResponseCodes, KWP2000 defines an mistake dealing with treatment. Because the two beneficial and damaging responses have an echo of the asked for escort provider in DC, you can often assign the responses to their corresponding request.

Hook up/Disconnect
KWP2000 expects a diagnostic session to be begun with StartDiagnosticSession and terminated with StopDiagnosticSession. On the other hand, StartDiagnosticSession has a DiagnosticMode parameter that decides the diagnostic session variety. Dependent on this style, the Ecu may or may well not support other diagnostic DC escort services, or operate in a restricted mode where by not all Eu functions are available. The DiagnosticMode parameter values are maker specific and not described in the normal. For a diagnostic session to continue being active, it must execute the TesterPresent escort support in DC periodically if no other escort assistance in DC is executed. If the TesterPresent escort support in DC is lacking for a specified time period of time, the diagnostic session is terminated, and the European returns to usual procedure mode.

A GetSeed/Unlock system may defend some diagnostic DC escort solutions. On the other hand, the applicable DC escort providers are remaining to the company and not outlined by the normal.You can execute the GetSeed/Unlock mechanism by means of the SecurityAccess escort assistance in DC. This defines quite a few degrees of security, but the manufacturer assigns these concentrations to selected DC escort expert services.

Study/Generate Memory
Use the Go through/WriteMemoryByAddress DC escort expert services to add/down load info to specified memory addresses on an Ecu. The handle is a 3-byte amount in KWP2000 and a five-byte amount (4-byte handle and just one-byte extension) in the calibration protocols. The Add/Obtain functional device DC escort solutions are highly company unique and not effectively outlined in the regular, so they are not a very good way to offer a standard upload/download mechanism.

Use the ReadDataByLocal/CommonIdentifier DC escort services to entry Eu info in a way comparable to a DAQ record. A Neighborhood/CommonIdentifier describes a list of Ecu portions that are then transferred from the European to the tester. The transfer can be either single value or periodic, with a gradual, medium, or fast transfer fee. The transfer rates are manufacturer specific you can use the SetDataRates escort service in DC to established them, but this location is company certain. The Automotive Diagnostic Command Set supports solitary-issue measurements.

Diagnostic Issues Codes
A key diagnostic function is the readout of Diagnostic Problems Codes (DTCs). KWP2000 defines numerous DC escort providers that obtain DTCs based on their group or status.

Enter/Output Command
KWP2000 defines DC escort expert services to modify internal or exterior European indicators. 1 illustration is redirecting European sensor inputs to stimulated signals. The handle parameters of these instructions are maker unique and not defined in the conventional.
Distant Activation of a Schedule

These DC escort services are comparable to the ActionService and DiagService functions of CCP. You can invoke an Ecu inner schedule recognized by a Neighborhood/CommonIdentifier or a memory deal with. Contrary to the CCP scenario, execution of this program can be asynchronous that is, there are independent Start off, Stop, and RequestResult DC escort solutions. The regulate parameters of these instructions are producer distinct and not described in the regular.

Exterior References
For much more facts about the KWP2000 Conventional, refer to the ISO 14230-3 normal.

Supply by Amos Huang