有如下程序,为MSDN中的示例代码,可是为什么运行时显示:
GetCommState failed with error 2, msdn中说明为:2 (ERROR_FILE_NOT_FOUND) : The system cannot find the file specified
可是我的电脑有串口呀,把"COM1"改为"COM2"也不行,代码如下:
#include "stdafx.h"#include <windows.h>
#include <tchar.h>
#include <stdio.h>
int main(int argc, char *argv[])
{
DCB dcb;
HANDLE hCom;
BOOL fSuccess;
TCHAR *pcCommPort = TEXT("COM1"); hCom = CreateFile( "COM1",
GENERIC_READ | GENERIC_WRITE,
0, // must be opened with exclusive-access
NULL, // default security attributes
OPEN_EXISTING, // must use OPEN_EXISTING
0, // not overlapped I/O
NULL // hTemplate must be NULL for comm devices
); if (hCom == INVALID_HANDLE_VALUE)
{
// Handle the error.
printf ("CreateFile failed with error %d.\n", GetLastError());
return (1);
} // Build on the current configuration, and skip setting the size
// of the input and output buffers with SetupComm. // SecureZeroMemory(&dcb, sizeof(DCB));
dcb.DCBlength = sizeof(DCB);
fSuccess = GetCommState(hCom, &dcb); if (!fSuccess)
{
// Handle the error.
printf ("GetCommState failed with error %d.\n", GetLastError());
return (2);
} // Fill in DCB: 57,600 bps, 8 data bits, no parity, and 1 stop bit. dcb.BaudRate = CBR_57600; // set the baud rate
dcb.ByteSize = 8; // data size, xmit, and rcv
dcb.Parity = NOPARITY; // no parity bit
dcb.StopBits = ONESTOPBIT; // one stop bit fSuccess = SetCommState(hCom, &dcb); if (!fSuccess)
{
// Handle the error.
printf ("SetCommState failed with error %d.\n", GetLastError());
return (3);
} _tprintf (TEXT("Serial port %s successfully reconfigured.\n"), pcCommPort);
return (0);
}
GetCommState failed with error 2, msdn中说明为:2 (ERROR_FILE_NOT_FOUND) : The system cannot find the file specified
可是我的电脑有串口呀,把"COM1"改为"COM2"也不行,代码如下:
#include "stdafx.h"#include <windows.h>
#include <tchar.h>
#include <stdio.h>
int main(int argc, char *argv[])
{
DCB dcb;
HANDLE hCom;
BOOL fSuccess;
TCHAR *pcCommPort = TEXT("COM1"); hCom = CreateFile( "COM1",
GENERIC_READ | GENERIC_WRITE,
0, // must be opened with exclusive-access
NULL, // default security attributes
OPEN_EXISTING, // must use OPEN_EXISTING
0, // not overlapped I/O
NULL // hTemplate must be NULL for comm devices
); if (hCom == INVALID_HANDLE_VALUE)
{
// Handle the error.
printf ("CreateFile failed with error %d.\n", GetLastError());
return (1);
} // Build on the current configuration, and skip setting the size
// of the input and output buffers with SetupComm. // SecureZeroMemory(&dcb, sizeof(DCB));
dcb.DCBlength = sizeof(DCB);
fSuccess = GetCommState(hCom, &dcb); if (!fSuccess)
{
// Handle the error.
printf ("GetCommState failed with error %d.\n", GetLastError());
return (2);
} // Fill in DCB: 57,600 bps, 8 data bits, no parity, and 1 stop bit. dcb.BaudRate = CBR_57600; // set the baud rate
dcb.ByteSize = 8; // data size, xmit, and rcv
dcb.Parity = NOPARITY; // no parity bit
dcb.StopBits = ONESTOPBIT; // one stop bit fSuccess = SetCommState(hCom, &dcb); if (!fSuccess)
{
// Handle the error.
printf ("SetCommState failed with error %d.\n", GetLastError());
return (3);
} _tprintf (TEXT("Serial port %s successfully reconfigured.\n"), pcCommPort);
return (0);
}
【我的电脑】->【右键】->【管理】->【设备管理】->右边设备树内找到:
【端口(COM和LPT)】若无,表明你机器上没有串口(这个很正常,现在新买的个人电脑一般都没有);
若有,看看他的儿子节点,后面的括号内就是COM号,比对下COM号是否对。例如,我的电脑上是这样的:
Prolific USB-to-Serial Bridge(COM4)这个意思是:我的机器上有一个串口口,他是COM4,看名字知道,这个串口是我用USB转换线转换出来的。
CreateFile 失败后,调用 GetLastError 获得错误信息。
【我的电脑】->【右键】->【管理】->【设备管理】->右边设备树内找到:
【端口(COM和LPT)】找到是com1还是com2,com3,一般是com1//初始化
CString initcom;
initcom="com1";
hComm=NULL;
initcom=CommPort;
CommPort="";
GetDlgItemText(IDC_COMBO,CommPort);
hComm=CreateFile(CommPort,GENERIC_READ|GENERIC_WRITE,0,NULL,OPEN_EXISTING,
FILE_FLAG_OVERLAPPED,NULL);
if(hComm==INVALID_HANDLE_VALUE)
{
CommPort=initcom;
AfxMessageBox("Create COM file error!",MB_ICONHAND);
return ;
}
AfxMessageBox("Create COM file success!",MB_ICONINFORMATION);
SetCommMask(hComm,EV_RXCHAR|EV_TXEMPTY);
SetupComm(hComm,1500,1500);
PurgeComm(hComm,PURGE_TXABORT|PURGE_RXABORT|PURGE_TXCLEAR|PURGE_RXCLEAR);
//define the timeout struction
COMMTIMEOUTS CommTimeOuts;
CommTimeOuts.ReadIntervalTimeout=MAXDWORD;
CommTimeOuts.ReadTotalTimeoutConstant=0;
CommTimeOuts.ReadTotalTimeoutMultiplier=0;
CommTimeOuts.WriteTotalTimeoutConstant=0;
CommTimeOuts.WriteTotalTimeoutMultiplier=0;//5000;
SetCommTimeouts(hComm,&CommTimeOuts);
DWORD BaudRate;
BaudRate=9600;
DCB dcb;
GetCommState(hComm,&dcb);
dcb.BaudRate=BaudRate;
dcb.ByteSize=7;
dcb.Parity=2;
dcb.StopBits=ONESTOPBIT;
dcb.fBinary=TRUE;
dcb.fParity=FALSE;
SetCommState(hComm,&dcb);//读数据
char* CCommandDlg::ReadComm(HANDLE hcom)
{
DWORD lpRead;
OVERLAPPED osRead={0};
char str[1024];
char strcom[1024];
memset(strcom,0,1024);
memset(str,0,1024);
if(hcom!=NULL && hcom!=INVALID_HANDLE_VALUE)
{
if(ReadFile(hcom,strcom,1024,&lpRead,&osRead))
{
for(int i=0;i<1024;i++)
str[i]=strcom[i];
return str;
}
else
{
// MessageBox("fail");
return "";
}
}
return "";
}
//写数据
void CCommandDlg::WriteDataToComm(char *buf, HANDLE hcom)
{
DWORD lpWriten;
OVERLAPPED osWrite={0}; CString str=""; if(hcom!=NULL && hcom!=INVALID_HANDLE_VALUE)
{
if(!WriteFile(hcom,buf,strlen(buf),&lpWriten,&osWrite))
{ str="Send Data To ";
str+=CommPort;
str+=':';
str+=buf;
str+="\r\n";
ShowEdit(str);
return ;
}
}
}
{