PVI通信 > PVI帮助信息 > PVI base system > PVICOM interface > User messages

必须输入SET_PVIFUNCTION（二进制0xfffffffc）作为用户信息的信息编号。消息句柄和消息参数可以由PVICOM应用程序自由使用。然而，请记住，为消息句柄（PVI函数的参数 "hResMsg"）输入零值会抑制响应（见 "请求和响应"部分）。对于不需要的消息句柄，可以输入常数PVI_HMSG_NIL。

为了读取用户消息，PVICOM应用程序需要调用 PviGetNextResponse 或PviXGetNextResponse函数。之后，程序与用户信息作为窗口信息的程序相同。

在PVICOM应用程序中，应在中央程序循环中循环调用函数PviGetNextResponse。这样就可以通过用户消息来控制整个程序过程。如果对PVI响应或事件数据的评估是在一个单独的线程中进行的，那么函数PviGetNextRespons可以很容易地集成在线程程序循环中。所有的异步PVICOM函数（异步和同步函数）和函数PviGetNextResponse（或PviXGetNextResponse）可以从不同的线程调用。

Visual C++的例子

#include <PviCom.h>
typedef bool (*T_RESPONSE_FUNC) (WPARAM, LPARAM, T_RESPONSE_INFO*, DWORD);
#define PVIOBJ_CNT 40
static DWORD PviObjLinkID[PVIOBJ_CNT];
static bool bExitProg;
static HANDLE hRespEvent;
void ExitProg ()
{
    bExitProg = TRUE;
    SetEvent (hRespEvent);
}
...
static void ObjectEvent (WPARAM wParam, LPARAM lParam, T_RESPONSE_INFO* pInfo, DWORD DataLen)
{
    INT   ErrCode;
    switch (pInfo->nType)
    {
        case POBJ_EVENT_DATA:
            // confirm object event and read data:
            ErrCode = PviReadResponse (wParam, pDataBf, DataLen);
            ...
        case POBJ_EVENT_ERROR:
            ...
        case POBJ_EVENT_DATAFORM:
            ...
    }
}
static void CreateResp (WPARAM wParam, LPARAM lParam, T_RESPONSE_INFO* pInfo, DWORD DataLen)
{
    DWORD LinkID
    INT   ErrCode;
    // confirm create response:
    ÉrrCode = PviCreateResponse (wParam, &LinkID)
    if (ErrCode != 0)
    {
        printf ("Object creation failed (Error=%d)\n", ErrCode);
        LinkID = 0;
    }
    PviObjLinkID[lParam] = LinkID;
}
static void GlobalEvent (WPARAM wParam, LPARAM lParam, T_RESPONSE_INFO* pInfo, DWORD DataLen)
{
    // confirm global event:
    PviReadResponse (wParam, NULL, 0);
    switch (pInfo->nType)
    {
        case POBJ_EVENT_PVI_CONNECT:
            printf ("PVI connection established\n");
        break;
        case POBJ_EVENT_PVI_DISCONN:
            printf ("PVI connection failed (Error=%d)\n", pInfo->ErrCode);
        break;
        case POBJ_EVENT_PVI_ARRANGE:
            // create all required PVI objects:
            ErrCode = PviCreateRequest ("@Pvi/LNINA2", POBJ_LINE, "CD=LnIna2",
                ObjectEvent, SET_PVIFUNCTION, 0, "EV=e", CreateResp, SET_PVIFUNCTION, 0);
            ...
            ErrCode = PviCreateRequest ("@Pvi/LNINA2/COM2/CPU/PVar1", POBJ_PVAR, "CD=PVar1",
                ObjectEvent, SET_PVIFUNCTION, 24, "EV=edf", CreateResp, SET_PVIFUNCTION, 24);
            ...
        break;
    }
}
int main ()
{
    INT   ErrCode;
    WPARAM wParam;
    LPARAM lParam;
    LPVOID hMsg;
    DWORD  DataLen;
    T_RESPONSE_INFO Info;
    T_RESPONSE_FUNC RespFunc;
    bExitProg = FALSE;
    hRespEvent = CreateEvent (NULL, FALSE, FALSE, NULL);
    if (hRespEvent == NULL)
    {
        printf ("Can't create system event\n");
        return (1);
    }
    ErrCode = PviInitialize (0, 0, "", NULL);
    if (ErrCode != 0)
    {
        printf ("Initialize failed (Error=%d)\n", ErrCode);
        return (1);
    }
    // define global events:
    ErrCode = PviSetGlobEventMsg (POBJ_EVENT_PVI_ARRANGE, GlobalEvent, SET_PVIFUNCTION, 0);
    ...
    // loop to control all response/event data:
    while (! bExitProg)
    {
        // get response/event data identification:
        ErrCode = PviGetNextResponse (&wParam, &lParam, &hMsg, hRespEvent);
        if (ErrCode != 0)
        {
            printf ("NextResponse failed (Error=%d)\n", ErrCode);
            break; // -> exit loop
        }
        if (wParam == 0)
           // wait for response/event data:
           WaitForSingleObject (hRespEvent, INFINITE);
        else
        {
            // read response/event data information:
            ErrCode = PviGetResponseInfo (wParam, NULL, &DataLen, &Info, sizeof (Info));
            if (ErrCode != 0)
            {
                if (ErrCode == 12055)
                    continue; // -> no response (skip error 12055)
                printf ("GetResponseInfo failed (Error=%d)\n", ErrCode);
                break; // -> exit loop
            }
            // call response/event function:
            RespFunc = (T_RESPONSE_FUNC) hMsg;
            RespFunc (wParam, lParam, &Info, DataLen);
        }
    }
    PviDeinitialize ();
    CloseHandle (hRespEvent);
    return (0);
}

Message function

Message function