我试图使用writefile和readfile函数通过串行端口连接发送和接收字符串。我必须异步执行此操作，因为要读取的字节数将始终不同，并且readfile只会挂起或阻塞，直到获得正确的字节数。现在我试图异步执行此操作，因此我的writefile函数将不会发送任何数据，并且我的readfile函数似乎会被跳过，因为下一行开始执行它，而不读取任何字符。不知道这是我的Overlapped结构还是我的超时问题。但我在这一刻卡住了。WriteFile()和ReadFile()异步无法写入或读取

超时

void Serial::OpenPortRead()

{

HANDLE sSerial = CreateFile(L"COM3",GENERIC_READ|GENERIC_WRITE,0,0,OPEN_EXISTING,FILE_FLAG_OVERLAPPED,0);

//Timeout Settings

COMMTIMEOUTS CommTimeouts;

GetCommTimeouts(sSerial, &CommTimeouts);

CommTimeouts.ReadIntervalTimeout = 5000;

CommTimeouts.ReadTotalTimeoutMultiplier = 2;

CommTimeouts.ReadTotalTimeoutConstant = 10;

CommTimeouts.WriteTotalTimeoutMultiplier = 50;

CommTimeouts.WriteTotalTimeoutConstant = 500;

//Port Settings

DCB dcbSerialParams = {0};

dcbSerialParams.DCBlength=sizeof(dcbSerialParams);

dcbSerialParams.BaudRate=CBR_19200;

dcbSerialParams.ByteSize=8;

dcbSerialParams.StopBits=ONESTOPBIT;

dcbSerialParams.Parity=NOPARITY;

SetCommState(sSerial,&dcbSerialParams);//Apply Settings to Handle

}

写文件功能

void Serial::WritePort(CString buffer)

{

DWORD bytes;//pointer to hold number of bytes written

USES_CONVERSION;

CW2A buf((LPCWSTR)buffer);//Convert unicode to ascii

OpenPortRead();

OVERLAPPED overlapped_structure;

memset(&overlapped_structure, 0, sizeof(overlapped_structure));

overlapped_structure.Offset = 0;

overlapped_structure.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);

WriteFile(sSerial, buf,strlen(buf),&bytes,&overlapped_structure);//Send string

}

读取文件功能

int Serial::ReadPort(CString buf){

OpenPortRead();// Open Serial Communication for reading

const int buffer_size = 10;

char buffer[10];//buffer to hold recieved string

memset (buffer, 0, buffer_size * sizeof (char));

int n, num,iTemp,i=0;

OVERLAPPED overlapped_structure;

memset(&overlapped_structure, 0, sizeof(overlapped_structure));

overlapped_structure.Offset = 0;

overlapped_structure.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);

DWORD bytesRead;//pointer to number bytes read

ReadFile(sSerial,&buffer,buffer_size,&bytesRead,&overlapped_structure);// begin read

//Used this function because return would be filled with extra raw data characters

buffer[n] = StringLength(buffer, &n);//find length of string returned

num = n;

+0

在WriteFile/ReadFile之后，您需要等待重叠事件。 –

2013-02-15 15:09:27

+0

感谢您的回复，但可能是一个帮助我的例子 –

2013-02-15 15:13:21

+1

重叠I/O的要点是它会在*稍后*完成，并且您的程序可以在正在进行时继续运行。等待它完全消除了首先使用它的要点。无论您的问题是什么，重叠的I/O都不是答案。 –

2013-02-15 15:22:11