User manual

CAN API reference

CANSetCallback, CANSetCallbackEx

CANSetCallback, CANSetCallbackEx — Defines an asynchronous callback function, which is called for

each incoming CAN telegram.

Syntax

#include <AnaGateDllCan.h>

typedef void (WINAPI * CAN_PF_CALLBACK)(int nIdentifier, const char *

pcBuffer, int nBufferLen, int nFlags, int hHandle);

int CANSetCallback(int hHandle, CAN_PF_CALLBACK pCallbackFunction);

typedef void (WINAPI * CAN_PF_CALLBACK_EX)(int nIdentifier, const char

* pcBuffer, int nBufferLen, int nFlags, int hHandle);

int CANSetCallbackEx(int hHandle, CAN_PF_CALLBACK_Ex

pCallbackFunctionEx);

Parameter

hHandle Valid access handle.

pCallbackFunction Function pointer to the private callback function. Set this parameter to

NULL to deactivate the callback function. The parameters of the callback

function are described in the documentation of the CANWrite funciton.

pCallbackFunctionEx Function pointer to the private callback function. Set this parameter to

NULL to deactivate the callback function. The parameters of the callback

function are described in the documentation of the CANWriteEx funciton.

Return value

Returns Null if successful, or an error value otherwise (Appendix A, Return Codes).

Description

Incoming CAN telegrams can bei received via a callback function, which can be set by a simple API call.

If a callback function us set, is will be called by the API asynchronous.

Caution

The callback fucntion is called from a thread which is started by the CAN API and which is

reading data from the socket. Because of this behaviour the callback code is executed by the

thread context of the API and therefore it uses it the heap memeory of the API DLL and not

the application program. So programming code should not use functions like new, delete,

alloc or free which allocate, free or reallocate heap memory inside the callback.

See the following example for using a callback.

#include <AnaGateCANDll.h>

// Defintion of a callback, which writes incoming CAN data with timestamp to console