Serial Port communication in C#

alfie max15

I am trying to start with serial port communication using C# for my project. So even though i am familiar with the C# language i am new into I/O Port communication and i seem to be having some problem with my code

using System;
using System.IO.Ports;

class Program
{
public static void Main ()
{
string portName = @"\\.\COM10";
_serialPort = new SerialPort (portName);
_serialPort.Close ();
}
}

i am getting an error :

Error 1 The name '_serialPort' does not exist in the current context c:\users\alfie\documents\visual studio 2012\Projects\serial\serial\Serial_port.cs

Someone pls help me get started with this. . Also i have tested with the following code and verified that the COM10 port is working and is of type "char"

class Program
{
static void Main (string[] args)
{
string portName = @"\\.\COM10";
IntPtr handle = CreateFile (portName, 0, 0, IntPtr.Zero, 3, 0x80, IntPtr.Zero);
if(handle == (IntPtr) (-1))
{
Console.WriteLine ("Could not open " + portName + ": " + new Win32Exception ().Message);
Console.ReadKey ();
return;
}

    FileType type = GetFileType (handle);
    Console.WriteLine ("File " + portName + " reports its type as: " + type);

    Console.ReadKey ();
}

\[DllImport ("kernel32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall, SetLastError = true)\]
public static extern IntPtr CreateFile (string lpFileName, uint dwDesiredAccess, uint dwShareMode, IntPtr SecurityAttributes, uint dwCreationDisposition, uint dwFlagsAndAttributes, IntPtr hTemplateFile);

\[DllImport ("kernel32.dll")\]
static extern FileType GetFileType (IntPtr hFile);

enum FileType : uint
{
    UNKNOWN = 0x0000,
    DISK = 0x0001,
    CHAR = 0x0002,
    PIPE = 0x0003,
    REMOTE = 0x8000,
}

}

Big Daddy Farang

The error message you are getting is telling us that you are using a variable called "_serialPort" but it is never defined. There needs to be a definition of that variable somewhere. Something like:

SerialPort _serialPort;

BDF The internet makes dumb people dumber and clever people cleverer. -- PaulowniaK

OriginalGriff

Well, you could start by declaring the variable...

using System;
using System.IO.Ports;

class Program
{
private SerialPort _serialPort = null; // <<---ADD THIS LINE
public static void Main ()
{
string portName = @"\\.\COM10";
_serialPort = new SerialPort (portName);
_serialPort.Close ();
}
}

The only instant messaging I do involves my middle finger.

alfie max15

Thanx... :) That worked like a charm... Sorry for my silly question....

alfie max15

OriginalGriff wrote:

using System; using System.IO.Ports; class Program { private SerialPort _serialPort = null; // <<---ADD THIS LINE public static void Main () { string portName = @"\\.\COM10"; _serialPort = new SerialPort (portName); _serialPort.Close (); } }

I tried this code... but i am getting this error...

An object reference is required for the non-static field, method, or property 'Program._serialPort'

OriginalGriff

:doh: Sorry, my bad! I forgot that Main is a static method! Add the word "static" between "private" and "SerialPort"

The only instant messaging I do involves my middle finger.

alfie max15

thanx.... that did the trick...:)

OriginalGriff

You're welcome!

The only instant messaging I do involves my middle finger.

David Knechtges

I know your question was answered by others, but I was wondering why you are using CreateFile instead of using the SerialPort class contained in the .NET framework? http://msdn.microsoft.com/en-us/library/system.io.ports.serialport.aspx[^]

OriginalGriff

If you look at the OP, there are two sections of code: the first using SerialPort is the one he has problems with, and the second is labeled as a test to prove the serial port works.

The only instant messaging I do involves my middle finger.