----串口发数据问题-----

[MeKing]

我在向串口发数据的过程中，总是发不出去，代码如下：
// Open the serial port.
hPort = CreateFile (_T("COM1"), // Pointer to the name of the port
GENERIC_READ | GENERIC_WRITE,
// Access (read/write) mode
0, // Share mode
NULL, // Pointer to the security attribute
OPEN_EXISTING,// How to open the serial port
0, // Port attributes
NULL); // Handle to port with attribute
// to copy
。。。。。

//send data
// Specify a set of events to be monitored for the port.
SetCommMask (hPort, EV_RXCHAR | EV_CTS | EV_DSR | EV_RLSD | EV_RING|EV_TXEMPTY|EV_RXFLAG );

PurgeComm(hPort,PURGE_RXCLEAR);
PurgeComm(hPort,PURGE_TXCLEAR);


//receive the SMS or GPS sign
while ( hPort != INVALID_HANDLE_VALUE )
{
// Wait for an event to occur for the port.
WaitCommEvent (hPort, &dwCommModemStatus, 0);

//Send the command of user
if (dwCommModemStatus & EV_TXEMPTY)
{
DWORD dwWcsLen=wcslen( tcsSmsSentData ),dwWritten=0;
if ( dwWcsLen >0 ){
__try
{
::EnterCriticalSection (&csMyCriticalSection);

BYTE *chEncode=new BYTE [ 58+dwWcsLen*4+3];
memset(chEncode,'\0',58+dwWcsLen*4+3);

chEncode[0]='\x02';
chEncode[1]='U';

BYTE byHigh,byLow;

//encode the mobile phone
for (int i=0;i<11;i++){
byHigh=HIBYTE(tcsMobilePhone[i]);
if ( HexToChar(byHigh,chEncode+2,i*4) == -1 )
break;
byLow=LOBYTE(tcsMobilePhone[i]);
if ( HexToChar(byLow,chEncode+2,i*4+2) == -1 )
break;
}

//insert the seperator symbol
chEncode[46]='0';
chEncode[47]='0';
chEncode[48]='3';
chEncode[49]='0';

//encode the SMS data
DWORD dwEncode=0;
for ( dwEncode;dwEncode<dwWcsLen;dwEncode++){
byHigh=HIBYTE(tcsSmsSentData[dwEncode]);
if ( HexToChar(byHigh,chEncode+50,dwEncode*4) == -1 )
break;
byLow=LOBYTE(tcsSmsSentData[dwEncode]);
if ( HexToChar(byLow,chEncode+50,dwEncode*4+2) == -1 )
break;
}

//append the end symbol
strcat((char*)chEncode,"000D000A");
int iEncodeLen=strlen((char*)chEncode);

BYTE *pByte=chEncode;
// iEncodeLen=strlen((char*)chEncode);
for ( i=0;i<iEncodeLen;i++){
WriteFile( hPort,
pByte++,
// chEncode,
// 58+dwWcsLen*4+2,
1,
&dwWritten,
0);
}

BYTE by=13;
WriteFile( hPort,&by,1, &dwWritten, 0);
by=10;
WriteFile( hPort,&by,1, &dwWritten, 0);

if ( dwWritten == dwWcsLen )
tcsSmsSentData[0]=L'\0';

delete []chEncode;
}
__finally
{
//退出临界区
::LeaveCriticalSection (&csMyCriticalSection);
}
}
}

如果我去掉：
if (dwCommModemStatus & EV_TXEMPTY)
后却可以将数据发出去，但是速度较慢，不知有没有哪位大侠有更好的方法？

[NowCan]

你为什么一开始就等待EV_TXEMPTY，这之前没有发过数据，怎么会有这个事件？

[NowCan]

你应该把
WaitCommEvent (hPort, &dwCommModemStatus, 0);
和判断放到最后。