Serial communication error.the error is it is giving the output of get has eror and port has erro

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C++

#include <stdio.h>
#include <windows.h>

void main()
{
	DWORD dwBytesRead, dwBytesWritten, dwPos;
	char c[7];
	LPWSTR port_name=malloc(5);
	int cnt,i,len;
	DCB obj_dcb;
	int m_baud_rate=CBR_110,  m_byte_size=1;

	HANDLE fd= CreateFile(port_name,GENERIC_READ|GENERIC_WRITE,0,NULL,CREATE_ALWAYS,FILE_ATTRIBUTE_NORMAL|FILE_FLAG_SEQUENTIAL_SCAN,NULL);
	
	
	if (fd == NULL)
		{ 
			printf("file doesnt exist");
		}
	else
	{
		if(GetCommState(fd,&obj_dcb)==0)
			{
				printf("get has problem");
			//	return FALSE;
		}
obj_dcb.BaudRate						= m_baud_rate;

	obj_dcb.DCBlength						= sizeof(obj_dcb);

	obj_dcb.Parity                          = 0;
	obj_dcb.ByteSize                        = m_byte_size;
	obj_dcb.StopBits                        = ONESTOPBIT ;
	obj_dcb.fBinary                         = TRUE;
	obj_dcb.fParity                         = FALSE;
	obj_dcb.fDsrSensitivity                 = TRUE;
	obj_dcb.fTXContinueOnXoff               = FALSE;
	obj_dcb.fOutX                           = FALSE;
	obj_dcb.fInX                            = FALSE;
	obj_dcb.fErrorChar                      = FALSE;
	obj_dcb.fNull                           = TRUE;
	obj_dcb.fRtsControl                     = RTS_CONTROL_ENABLE;
	obj_dcb.fAbortOnError                   = TRUE;
	if(SetCommState(fd,&obj_dcb)==0)
		{	printf("eror in port");
//			return FALSE;
		}
		
			for(i=0;i<=4 ;i++)
					{	
						c[i] = getchar();	
					}
						c[i] = '\0';

				dwBytesWritten=strlen(c) ;
						
				WriteFile (fd,c,dwBytesWritten,&dwBytesWritten, NULL);
			
		
	}
			c[0] = '\0';

	
				CloseHandle(fd);
		
				fd= CreateFile(TEXT("d:\\temp.txt"),GENERIC_READ,0,NULL,OPEN_ALWAYS,FILE_ATTRIBUTE_NORMAL|FILE_FLAG_SEQUENTIAL_SCAN,NULL);
	
	if(fd == NULL)
		{	
			printf("do exist");
		}
	else
		{
				dwBytesRead=sizeof(char);
				ReadFile (fd, c, 1, &dwBytesRead, NULL);			
				printf("%s",c);
		}
	
}

[edit]SHOUTING removed - OriginalGriff[/edit]

Posted 18-Apr-12 22:58pm

heenagoyal11

Updated 18-Apr-12 23:07pm

v4

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Comments

Prasad_Kulkarni 19-Apr-12 5:00am

Where's error & Where's your question??

OriginalGriff 19-Apr-12 5:00am

And the problem is?
I see your subject, I see a code dump.
You forgot to tell us what the problem is.
Remember that we can't see your screen, access your HDD, or read your mind.
Use the "Improve question" widget to edit your question and provide better information.

OriginalGriff 19-Apr-12 5:02am

DON'T SHOUT. Using all capitals is considered shouting on the internet, and rude (using all lower case is considered childish). Use proper capitalisation if you want to be taken seriously.

heenagoyal11 19-Apr-12 5:06am

the error is it is giving the output of get has eror and port has error

2 solutions

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Jochen Arndt · Answer 1 · 2012-04-18T23:15:00

This line contains multiple errors:

C++

CreateFile(port_name,GENERIC_READ|GENERIC_WRITE,0,NULL,CREATE_ALWAYS,FILE_ATTRIBUTE_NORMAL|FILE_FLAG_SEQUENTIAL_SCAN,NULL);

port_name is not initialized
dwCreationDisposition must be OPEN_EXISTING for serial ports
dwFlagsAndAttributes should be 0 for serial ports

Try

C++

LPWSTR port_name = L"COM1";
CreateFile(port_name, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL);

I did not check the remaining code for other errors.

[UPDATE checking for more errors]

The byte size is a bit count:

C++

// Wrong
//int m_byte_size = 1;
// Correct is 7 or 8
int m_byte_size = 8;

CreateFile returns INVALID_HANDLE_VALUE upon errors:

C++

// Don't use this
//if (fd == NULL)
// But this
if (fd == INVALID_HANDLE_VALUE)

Andy411 · Answer 2 · 2012-04-18T23:19:00

Solution 2

You did not assign a port name.
You just do

C++

LPWSTR port_name=malloc(5);

and some lines later you try to open the port without assigning a Com-Port.

For the first test on COM1 just try

C++

HANDLE fd = CreateFile( _T("\\\\.\\COM1"),  
                    GENERIC_READ | GENERIC_WRITE, 
                    0, 
                    0, 
                    OPEN_EXISTING,
                    0,
                    0);

Take a look at CreateFile function[^]

and Serial Communications in Win32[^]

Hope it helps..

Posted 18-Apr-12 23:19pm

Andy411

Comments

heenagoyal11 19-Apr-12 5:28am

what is_T?

Andy411 19-Apr-12 5:40am

It's a macro like TEXT

heenagoyal11 19-Apr-12 6:04am

but is creating error in my code?

Andy411 20-Apr-12 3:07am

Take a look at
Unicode Programming Summary
and
Teach me what is _T?