access serial port by visual C++ - c++

Question

I want to access serial port by visual c++
I get the program from internet but when I run the program, it seems the port can not open
here my program serialClass.cpp
#ifndef SERIALCLASS_H_INCLUDED
#define SERIALCLASS_H_INCLUDED
#define ARDUINO_WAIT_TIME 2000
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
class Serial
{
private:
HANDLE hSerial;
bool connected;
COMSTAT status;
DWORD errors;
public:
Serial(char *portName);
//Serial();
~Serial();
int ReadData(char *buffer, unsigned int nbChar);
bool WriteData(char *buffer, unsigned int nbChar);
bool IsConnected();
};
#endif // SERIALCLASS_H_INCLUDED
and my Serial.cpp
#include "SerialClass.h"
Serial::Serial(char *portName)
//Serial::Serial()
{
//We're not yet connected
this->connected = false;
//Try to connect to the given port throuh CreateFile
this->hSerial = CreateFile((LPCWSTR) portName,
GENERIC_READ | GENERIC_WRITE,
0,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
0);
//Check if the connection was successfull
if(this->hSerial==INVALID_HANDLE_VALUE)
{
//If not success full display an Error
if(GetLastError()==ERROR_FILE_NOT_FOUND){
printf("ERROR: Handle was not attached. Reason: COM1 not available.\n");
}
else
{
printf("ERROR!!!");
}
}
else
{
//If connected we try to set the comm parameters
DCB dcbSerialParams = {0};
//Try to get the current
if (!GetCommState(this->hSerial, &dcbSerialParams))
{
//If impossible, show an error
printf("failed to get current serial parameters!");
}
else
{
//Define serial connection parameters for the arduino board
dcbSerialParams.BaudRate=CBR_19200;
dcbSerialParams.ByteSize=8;
dcbSerialParams.StopBits=ONESTOPBIT;
dcbSerialParams.Parity=NOPARITY;
dcbSerialParams.fOutX=TRUE;
dcbSerialParams.fInX=TRUE;
//Set the parameters and check for their proper application
if(!SetCommState(hSerial, &dcbSerialParams))
{
printf("ALERT: Could not set Serial Port parameters");
}
else
{
//If everything went fine we're connected
this->connected = true;
//We wait 2s as the arduino board will be reseting
//Sleep(ARDUINO_WAIT_TIME);
printf("Current Settings\n Baud Rate %d\n Parity %d\n Byte Size %d\n Stop Bits %d", dcbSerialParams.BaudRate,
dcbSerialParams.Parity, dcbSerialParams.ByteSize, dcbSerialParams.StopBits);
}
}
}
}
Serial::~Serial()
{
//Check if we are connected before trying to disconnect
if(this->connected)
{
//We're no longer connected
this->connected = false;
//Close the serial handler
CloseHandle(this->hSerial);
}
}
int Serial::ReadData(char *buffer, unsigned int nbChar)
{
//Number of bytes we'll have read
DWORD bytesRead;
//Number of bytes we'll really ask to read
unsigned int toRead;
//Use the ClearCommError function to get status info on the Serial port
ClearCommError(this->hSerial, &this->errors, &this->status);
//Check if there is something to read
if(this->status.cbInQue>0)
{
//If there is we check if there is enough data to read the required number
//of characters, if not we'll read only the available characters to prevent
//locking of the application.
if(this->status.cbInQue>nbChar)
{
toRead = nbChar;
}
else
{
toRead = this->status.cbInQue;
}
//Try to read the require number of chars, and return the number of read bytes on success
if(ReadFile(this->hSerial, buffer, toRead, &bytesRead, NULL) && bytesRead != 0)
{
return bytesRead;
}
}
//If nothing has been read, or that an error was detected return -1
return -1;
}
bool Serial::WriteData(char *buffer, unsigned int nbChar)
{
DWORD bytesSend;
//Try to write the buffer on the Serial port
if(!WriteFile(this->hSerial, (void *)buffer, nbChar, &bytesSend, 0))
{
//In case it don't work get comm error and return false
ClearCommError(this->hSerial, &this->errors, &this->status);
return false;
}
else
return true;
}
bool Serial::IsConnected()
{
//Simply return the connection status
return this->connected;
}
The result is always
ERROR: Handle was not attached. Reason: COM1 not available.
any body can help?

Answer 1

The problem is with casting to a wide string instead of converting, I replaced that part of the code opening the port with the following and it worked:
wchar_t wcPort[64];
size_t convertedChars = 0;
mbstowcs_s(&convertedChars, wcPort, strlen(portName), portName, _TRUNCATE);
this->hSerial = CreateFile(wcPort,
GENERIC_READ | GENERIC_WRITE,
0,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
0);
Or as Ben Voigt has pointed out in a comment you could also call the CreateFileA variant so that Windows performs the conversion for you.