//#include "StdAfx.h"
#include <stdio.h>
#include <windows.h>
#include <winbase.h>
#include <iostream>
#include <tchar.h>
using namespace std;
int main()
{
int com = 'COM2';
string data = "\n 010400 \n";
char output[32];
//unsigned int length = 0;
DCB config = {0};
bool abContinue = true;
DWORD dwBytesWritten;
DWORD dwBytesRead;
int isRead = false;
HANDLE m_hCommPort = ::CreateFile(L"COM2",GENERIC_READ|GENERIC_WRITE,//access ( read and write)
0,//(share) 0:cannot share the COM port
0,//security (None)
OPEN_EXISTING,// creation : open_existing
0,// we dont want overlapped operation
0// no templates file for COM port...
);
config.DCBlength = sizeof(config);
if((GetCommState(m_hCommPort,&config) == 0))
{
printf("Get configuration port has a problem.");
return FALSE;
}
config.Baudrate = 9600;
config.StopBits = OnesTOPBIT;
config.Parity = PARITY_NONE;
config.ByteSize = DATABITS_8;
config.fDtrControl = 0;
config.fRtsControl = 0;
if (!SetCommState(m_hCommPort,&config))
{
printf( "Failed to Set Comm State Reason: %d\n",GetLastError());
//return E_FAIL;
}
printf("Current Settings\n Baud Rate %d\n Parity %d\n Byte Size %d\n Stop Bits %d",config.Baudrate,config.Parity,config.ByteSize,config.StopBits);
int isWritten = WriteFile(m_hCommPort,&data,(DWORD) sizeof(data),&dwBytesWritten,NULL);
//memset(output,sizeof(output));
while (abContinue)
{
isRead = ReadFile(m_hCommPort,output,sizeof(output),&dwBytesRead,NULL);
if(!isRead)
{
abContinue = false;
break;
}
}
cin.get();
}
我在从com端口读取时遇到问题.如果我单步执行代码,它将进入“isRead = ReadFile(m_hCommPort,& dwBytesRead,NULL);”并且没有回来……这是我第一次尝试这个没有成功.
解决方法
在打开文件之后,在尝试使用它之前,您可能会尝试使用类似的代码：
COMMTIMEOUTS timeouts;
timeouts.ReadIntervalTimeout = 1;
timeouts.ReadTotalTimeoutMultiplier = 1;
timeouts.ReadTotalTimeoutConstant = 1;
timeouts.WritetotalTimeoutMultiplier = 1;
timeouts.WritetotalTimeoutConstant = 1;
if (!SetCommTimeouts(m_hCommPort,&timeouts))
// setting timeouts Failed.
编辑：也许更容易从一些有效的代码开始,并使它做你想做的,而不是试图让你的代码工作.这是一个简单的终端程序.它极端极简,但确实有效(至少足以让我看到GPS的输出,例如).从任何人(最不重要的是我)称之为复杂的方面来说,这是一个漫长的道路,但至少应该给出一些如何开始的想法.
#include <stdio.h>
#include <conio.h>
#include <string.h>
#define STRICT
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
void system_error(char *name) {
// Retrieve,format,and print out a message from the last error. The
// `name' that's passed should be in the form of a present tense noun
// (phrase) such as "opening file".
//
char *ptr = NULL;
FormatMessage(
FORMAT_MESSAGE_ALLOCATE_BUFFER |
FORMAT_MESSAGE_FROM_SYstem,GetLastError(),(char *)&ptr,1024,NULL);
fprintf(stderr,"\nError %s: %s\n",name,ptr);
LocalFree(ptr);
}
int main(int argc,char **argv) {
int ch;
char buffer[1];
HANDLE file;
COMMTIMEOUTS timeouts;
DWORD read,written;
DCB port;
HANDLE keyboard = GetStdHandle(STD_INPUT_HANDLE);
HANDLE screen = GetStdHandle(STD_OUTPUT_HANDLE);
DWORD mode;
char port_name[128] = "\\\\.\\COM3";
char init[] = ""; // e.g.,"ATZ" to completely reset a modem.
if ( argc > 2 )
sprintf(port_name,"\\\\.\\COM%c",argv[1][0]);
// open the comm port.
file = CreateFile(port_name,GENERIC_READ | GENERIC_WRITE,NULL,OPEN_EXISTING,NULL);
if ( INVALID_HANDLE_VALUE == file) {
system_error("opening file");
return 1;
}
// get the current DCB,and adjust a few bits to our liking.
memset(&port,sizeof(port));
port.DCBlength = sizeof(port);
if ( !GetCommState(file,&port))
system_error("getting comm state");
if (!BuildCommDCB("baud=19200 parity=n data=8 stop=1",&port))
system_error("building comm DCB");
if (!SetCommState(file,&port))
system_error("adjusting port settings");
// set short timeouts on the comm port.
timeouts.ReadIntervalTimeout = 1;
timeouts.ReadTotalTimeoutMultiplier = 1;
timeouts.ReadTotalTimeoutConstant = 1;
timeouts.WritetotalTimeoutMultiplier = 1;
timeouts.WritetotalTimeoutConstant = 1;
if (!SetCommTimeouts(file,&timeouts))
system_error("setting port time-outs.");
// set keyboard to raw reading.
if (!GetConsoleMode(keyboard,&mode))
system_error("getting keyboard mode");
mode &= ~ ENABLE_PROCESSED_INPUT;
if (!SetConsoleMode(keyboard,mode))
system_error("setting keyboard mode");
if (!EscapeCommFunction(file,CLRDTR))
system_error("clearing DTR");
Sleep(200);
if (!EscapeCommFunction(file,SETDTR))
system_error("setting DTR");
if ( !WriteFile(file,init,sizeof(init),&written,NULL))
system_error("writing data to port");
if (written != sizeof(init))
system_error("not all data written to port");
// basic terminal loop:
do {
// check for data on port and display it on screen.
ReadFile(file,buffer,sizeof(buffer),&read,NULL);
if ( read )
WriteFile(screen,read,NULL);
// check for keypress,and write any out the port.
if ( kbhit() ) {
ch = getch();
WriteFile(file,&ch,1,NULL);
}
// until user hits ctrl-backspace.
} while ( ch != 127);
// close up and go home.
CloseHandle(keyboard);
CloseHandle(file);
return 0;
}