Credit: Chris Tacke

This code was written for reading and writing 1 or 2 bytes to and from CE ports for analog and digital I/O, so it will require some massaging for larger streams like COM port transfer. Still, it's a start.

using System;
using System.Runtime.InteropServices;

namespace ADSLibrary
{
	public class CEPorts
	{
		public static bool PortIsValid(string PortName)
		{
			int hPort = CEAPI.INVALID_HANDLE_VALUE;

			// open port
			hPort = CEAPI.CreateFile(PortName, CEAPI.GENERIC_WRITE, 0, 0, CEAPI.OPEN_EXISTING, 0, 0);

			// check for success
			if(hPort == CEAPI.INVALID_HANDLE_VALUE)
			{
				if(CEAPI.GetLastError() == 55)
					return false;
				else
				{
					Exception e = new Exception("Failed to open port '" + PortName + "': " + Convert.ToString(CEAPI.GetLastError()));
					throw e;
				}
			}

			CEAPI.CloseHandle(hPort);

			return true;
		}

		public static bool WritePort(string PortName, byte Value)
		{
			int hPort = CEAPI.INVALID_HANDLE_VALUE;
			int dwSize = 1;
			byte[] buffer = {Value};

			// open port
			hPort = CEAPI.CreateFile(PortName, CEAPI.GENERIC_WRITE, 0, 0, CEAPI.OPEN_EXISTING, 0, 0);

			// check for success
			if(hPort == CEAPI.INVALID_HANDLE_VALUE)
			{
				Exception e = new Exception("Failed to open port '" + PortName + "': " + Convert.ToString(CEAPI.GetLastError()));
				throw e;
			}
			
			// write to port
			if(!CEAPI.WriteFile(hPort, buffer, 1, ref dwSize, 0))
			{
				Exception e = new Exception("Unable to write to port '" + PortName + "': " + Convert.ToString(CEAPI.GetLastError()));
				throw e;
			}

			// close port
			if(!CEAPI.CloseHandle(hPort))
			{
				Exception e = new Exception("Unable to close port '" + PortName + "': " + Convert.ToString(CEAPI.GetLastError()));
				throw e;
			}

			return true;
		}

		public static byte ReadPortByte(string PortName)
		{
			int hPort = CEAPI.INVALID_HANDLE_VALUE;
			int read = 0;
			byte[] buffer = new byte[1];


			// open port
			hPort = CEAPI.CreateFile(PortName, CEAPI.GENERIC_READ, 0, 0, CEAPI.OPEN_EXISTING, 0, 0);

			// check for success
			if(hPort == CEAPI.INVALID_HANDLE_VALUE)
			{
				Exception e = new Exception("Failed to open port '" + PortName + "': " + Convert.ToString(CEAPI.GetLastError()));
				throw e;
			}
			
			// read port value
			if(!CEAPI.ReadFile(hPort, buffer, 1, ref read, 0))
			{
				Exception e = new Exception("Failed to read port '" + PortName + "': " + Convert.ToString(CEAPI.GetLastError()));
				throw e;
			}

			if(read != 1)
			{
				Exception e;
				e = new Exception("BYTE block size specified but " + Convert.ToString(read) + " bytes returned");

				throw e;
			}

			// close port
			if(!CEAPI.CloseHandle(hPort))
			{
				Exception e = new Exception("Unable to close port '" + PortName + "': " + Convert.ToString(CEAPI.GetLastError()));
				throw e;
			}

			return buffer[0];
		}

		public static ushort ReadPortWord(string PortName)
		{
			int hPort = CEAPI.INVALID_HANDLE_VALUE;
			int read = 0;
			byte[] buffer = new byte[2];


			// open port
			hPort = CEAPI.CreateFile(PortName, CEAPI.GENERIC_READ, 0, 0, CEAPI.OPEN_EXISTING, 0, 0);

			// check for success
			if(hPort == CEAPI.INVALID_HANDLE_VALUE)
			{
				Exception e = new Exception("Failed to open port '" + PortName + "': " + Convert.ToString(CEAPI.GetLastError()));
				throw e;
			}
			
			// read port value
			if(!CEAPI.ReadFile(hPort, buffer, 2, ref read, 0))
			{
				Exception e = new Exception("Failed to read port '" + PortName + "': " + Convert.ToString(CEAPI.GetLastError()));
				throw e;
			}

			if(read != 2)
			{
				Exception e;
				e = new Exception("WORD block size specified but " + Convert.ToString(read) + " bytes returned");

				throw e;
			}

			// close port
			if(!CEAPI.CloseHandle(hPort))
			{
				Exception e = new Exception("Unable to close port '" + PortName + "': " + Convert.ToString(CEAPI.GetLastError()));
				throw e;
			}
			
			// convert the 2-byte array to a word
			return (ushort)((buffer[1] << 8) + buffer[0]);
		}
	}

	internal class CEAPI
	{
		public const uint GENERIC_READ = 0x80000000;
		public const uint GENERIC_WRITE = 0x40000000;
		public const int OPEN_EXISTING = 3;
		public const int INVALID_HANDLE_VALUE = -1;

		[DllImport("coredll.dll", EntryPoint="WriteFile")]
		public static extern bool WriteFile(
			int hFile, 
			Byte[] lpBuffer, 
			int nNumberOfBytesToWrite, 
			ref int lpNumberOfBytesWritten, 
			int lpOverlapped);

		[DllImport("coredll.dll", EntryPoint="ReadFile")]
		public static extern bool ReadFile(
			int hFile,
			byte[] lpBuffer,
			int nNumberOfBytesToRead,
			ref int lpNumberOfBytesRead,
			int lpOverlapped);

		[DllImport("coredll.dll", EntryPoint="CreateFile")]
		public static extern int CreateFile(
			string lpFileName,
			uint dwDesiredAccess,
			int dwShareMode,
			int lpSecurityAttributes,
			int dwCreationDisposition,
			int dwFlagsAndAttributes,
			int hTemplateFile);

		[DllImport("coredll.dll", EntryPoint="CloseHandle")]
		public static extern bool CloseHandle(int hObject);

		[DllImport("coredll.dll", EntryPoint="GetLastError")]
		public static extern int GetLastError();
	}

}

i have few questions:
does c# have any comport class or IO to do that
i thought no, otherwise,you don't wrapping api

about import dll, the internal CEAPI(it is inner wrapper class & partly wrapped related api)
doing that is very huge!
1 i don't know which dll
2 i don't know which methods
3 i don't know which constants eg INVALID_HANDLE_VALUE = -1

2ndly, using createfile(portname...) the portname is "COM1:"or etc
can you give me some hints on pass the "hayes compatible on COM1:"
instead of "COM1:"

3rdly,i don't understand. (buffer[0] << 8) + buffer[1] intsead
(ushort)((buffer[1] << 8) + buffer[0]);

Thanks in advance,
tang, sze yee (c2)

Chris,

code that you have posted has problems. it throws notsupportedexception when CreateFile is called. i am testing it on iPaq having win ce 4.XX

Rizwan Ansari

Please switch to IO.Serial namespace to program serial ports on your device.

Hello Chris,

Thanks for posting this code.

I am using win ce 4.2 device, c#.net and smartdeviceapplication project type. I have to print to a mobile printer using a bluetooth adapter on a serial port.

Using the class code you posted, i am able to Open the port(CreateFile) but when i write to the port(WriteFile) it throws 1359. I am not able to write to COM3 port.

If i try to open any other port 1 to 2 and 4 to 11, it throws 55 (Failed to open port COM#)

Please help me.

With best regards,

Gulame

Hi sir,

I use your code it perfect adn usefull. before anything.. Thank you very much.

I use this code to read GPS from Com1 (It's Phsycal) then I have good response .But in this code I have some problem. I don't no it's problem on my device or other.

This Code on read
for (int i = 0; i < buffer_read.Length; i++)
{
if (buffer_read[i] != 0)
{
tmp = Convert.ToChar(buffer_read[i]);
if (found_sign) {
if (tmp == 'G') {
start_read = true;
}
}
if (tmp == '$')
{
found_sign = true;
}
else {
found_sign = false;
}
if (start_read)
{
str_read += tmp;
sum++;
}
}

}

*****str_read is reponse of this code

My device COM1 data is
...
... (Some time it's have some line before this but some time it not I don't know why)

$PSRFXTXTWK: 1452*4B
$PSRFXTXTPOS: -1351940 593620 1893803*28
$PSRFXTXTCLK: 96638*03
$PSRFXTXTCHNL: 15*5F
$PSRFXTXTBAUD RATE: 57600*51
$GPGGA,011042.724,,,,,0,00,,,,M,0.0,,M,,0000*51 // line 6
$GPGSA,A,1,,,,,,,,,,,,,,,*1E //line 7
$GPRMC,011042.72,V,,,,,,,071107,,,N*4A //line 8

I know last 3 line is GPS data but. I thing it not have Lat,Long (On line 6). but why some program can read it. And am not?

Now I thing
1. My GPS that I get it not all data.
2. My code is Decode for ture way.
3. I can't Synchronize i use beginInvoke for read data and Thread(because I don't know how can I syn it). I do event for 1 secound and I get this data

If you or other people on this board want to do see my project please POST your mail or send mail to cosciisoft@hotmail.com

Sory for my bad english

Thank you for all code
Wanchai ,
Open Source developer on Thailand