概述：我试图通过在从串行端口读取的每个字节之间发出长延迟来触发溢出错误指示。长话短说 - 我不明白这个事件。
测试：DTE配置为920000BPS 8N1，无流量控制。DTE 通过“Silicon Labs CP210x USB to UART Bridge”设备连接到我的 Windows10 主机。
提供的代码片段打开端口，调用 SetCommMask 函数。在循环中对 ReadFile 的每次调用之间插入了 10 秒的延迟。DTE 以稳定的速率连续发送数据。
问题：我没有收到来自 WaitCommEvent 的任何溢出信号。
问题：我的代码有问题吗？USB驱动程序有一些已知的限制吗？我是否需要使用流控制来引起关于溢出事件的注意？
#include <Windows.h>
#include <stdio.h>
#include <string.h>
int main(void)
{
HANDLE hComm; // Handle to the Serial port
BOOL Status; // Status
DCB dcbSerialParams = { 0 }; // Initializing DCB structure
COMMTIMEOUTS timeouts = { 0 }; //Initializing timeouts structure
char SerialBuffer[64] = { 0 }; //Buffer to send and receive data
DWORD BytesWritten = 0; // No of bytes written to the port
DWORD dwEventMask; // Event mask to trigger
char ReadData; //temperory Character
DWORD NoBytesRead; // Bytes read by ReadFile()
unsigned char loop = 0;
wchar_t pszPortName[10] = { 0 }; //com port id
wchar_t PortNo[20] = { 0 }; //contain friendly name
//Enter the com port id
do
{
printf_s("Enter the Com Port: ");
wscanf_s(L"%s", pszPortName, (unsigned)_countof(pszPortName));
swprintf_s(PortNo, 20, L"\\\\.\\%s", pszPortName);
//Open the serial com port
hComm = CreateFile(PortNo, //friendly name
GENERIC_READ | GENERIC_WRITE, // Read/Write Access
0, // No Sharing, ports cant be shared
NULL, // No Security
OPEN_EXISTING, // Open existing port only
0, // Non Overlapped I/O
NULL); // Null for Comm Devices
if (hComm == INVALID_HANDLE_VALUE)
{
printf_s("\n Port can't be opened\n\n");
break;
}
//Setting the Parameters for the SerialPort
dcbSerialParams.DCBlength = sizeof(dcbSerialParams);
Status = GetCommState(hComm, &dcbSerialParams); //retreives the current settings
if (Status == FALSE)
{
printf_s("\nError to Get the Com state\n\n");
break;
}
dcbSerialParams.BaudRate = 920000;//CBR_9600; //BaudRate = 9600
dcbSerialParams.ByteSize = 8; //ByteSize = 8
dcbSerialParams.StopBits = ONESTOPBIT; //StopBits = 1
dcbSerialParams.Parity = NOPARITY; //Parity = None
Status = SetCommState(hComm, &dcbSerialParams);
if (Status == FALSE)
{
printf_s("\nError to Setting DCB Structure\n\n");
break;
}
//Setting Timeouts
timeouts.ReadIntervalTimeout = 50;
timeouts.ReadTotalTimeoutConstant = 50;
timeouts.ReadTotalTimeoutMultiplier = 10;
timeouts.WriteTotalTimeoutConstant = 50;
timeouts.WriteTotalTimeoutMultiplier = 10;
if (SetCommTimeouts(hComm, &timeouts) == FALSE)
{
printf_s("\nError to Setting Time outs");
break;
}
//Setting Receive Mask
Status = SetCommMask(hComm, EV_ERR| EV_RX80FULL| EV_BREAK/*EV_RXCHAR*/);
if (Status == FALSE)
{
printf_s("\nError to in Setting CommMask\n\n");
break;
}
//Read data and store in a buffer
do
{
Status = ReadFile(hComm, &ReadData, sizeof(ReadData), &NoBytesRead, NULL);
//Setting WaitComm() Event
Sleep(10000); /* Ten seconds */
Status = WaitCommEvent(hComm, &dwEventMask, NULL); //Wait for the character to be received
if (Status == FALSE)
{
printf_s("\nError! in Setting WaitCommEvent()\n\n");
break;
}
SerialBuffer[loop] = ReadData;
++loop;
} while (NoBytesRead > 0);
--loop; //Get Actual length of received data
printf_s("\nNumber of bytes received = %d\n\n", loop);
//print receive data on console
printf_s("\n\n");
int index = 0;
for (index = 0; index < loop; ++index)
{
printf_s("%c", SerialBuffer[index]);
}
printf_s("\n\n");
} while (0);
CloseHandle(hComm);//Closing the Serial Port
system("pause");
return 0;
}