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Introduction

j2534-logger is a shim DLL that sits between a J2534-application and a J2534-device. It records debugging information about the API calls to a circular memory-buffer and can write that information to a file.

Details

This library exports all standard PassThru functions, plus a few new functions that control the logging.

PassThruLoadLibrary

This function causes the shim to load a J2534 DLL. This function must be called one time before any other function with the exception of PassThruWriteToLog, PassThruSaveLog, and PassThruGetLastError. Any other function called before a successful call to PassThruLoadLibrary will return an error. If the DLL exists and was loaded successfully, a value of STATUS_NOERROR is returned.

C/C++ Prototype

extern "C" long WINAPI PassThruLoadLibrary(
   char *szFunctionLibrary    // Pointer to FunctionLibrary string. This must
                              // contain a path to a v04.04 J2534 DLL.
);

Return Values

Definition	Description
STATUS_NOERROR	Function call successful
ERR_NULL_POINTER	NULL pointer supplied where a valid pointer is required
ERR_FAILED	Undefined error, use PassThruGetLastError for text description

PassThruWriteToLog

This function write a string into the debug log. There is no limit to the length of this string, but a single line (with no newline character) is recommended because the text will output like:

0.00s ** 'Vehicle identified, ready to reflash!'

Two versions of this function exist, one accepts an ANSI string and the other accepts a UNICODE string. The log uses UNICODE for the internal memory-buffer and will save to a UTF-8 file.

C/C++ Prototype

extern "C" long WINAPI PassThruWriteToLogA(
   char *szMsg                // Pointer to an ANSI string
);

extern "C" long WINAPI PassThruWriteToLogW(
   wchar_t *szMsg             // Pointer to a UNICODE string
);

Return Values

Definition	Description
STATUS_NOERROR	Function call successful
ERR_NULL_POINTER	NULL pointer supplied where a valid pointer is required
ERR_FAILED	Undefined error, use PassThruGetLastError for text description

PassThruSaveLog

This function saves the debug log from an internal circular memory-buffer to a UTF-8 encoded file. If the function is successful a value of STATUS_NOERROR is returned and the memory-buffer is cleared.

This function may be called at any time, even without a J2534 DLL loaded.

C/C++ Prototype

extern "C" long WINAPI PassThruSaveLog(
   char *szFilename           // Pointer to the output filename string
);

Return Values

Definition	Description
STATUS_NOERROR	Function call successful
ERR_NULL_POINTER	NULL pointer supplied where a valid pointer is required
ERR_FAILED	Undefined error, use PassThruGetLastError for text description

PassThruUnloadLibrary

This function causes the shim to unload the J2534 DLL. After this call, any function except PassThruWriteToLog, PassThruSaveLog, PassThruGetLastError, and PassThruLoadLibrary will return ERR_FAILED. If the function is successful a value of STATUS_NOERROR is returned.

C/C++ Prototype

extern "C" long WINAPI PassThruUnloadLibrary();

Return Values

Definition	Description
STATUS_NOERROR	Function call successful
ERR_FAILED	Undefined error, use PassThruGetLastError for text description

PassThruGetLastError

This function returns the text string description for an error detected during the last function call. Like SAE J2534-1, the buffer pointed to by pErrorDescription is allocated by the application and must be at least eighty (80) characters. The function can be called at any time, even before calling PassThruLoadLibrary or after calling PassThruUnloadLibrary.

The string describes an internal error if the shim has not loaded a J2534 DLL, if a DLL is loaded but does not provide an export for the last function call, or if the last function call was PassThruLoadLibrary, PassThruUnloadLibrary, PassThruWriteToLog, or PassThruSaveLog. In all other cases string comes from the J2534 DLL's function PassThruGetLastError.

C/C++ Prototype

extern “C” long WINAPI PassThruGetLastError(
   char *pErrorDescription    // Pointer to error description string
)

Return Values

Definition	Description
STATUS_NOERROR	Function call successful
ERR_NULL_POINTER	NULL pointer supplied where a valid pointer is required