Serial Communication in C# Express

[Haluk Gokmen]

I had an inquiry about the use of MSComm OCX in a C# application awhile
ago and I really appreciated Nicholas Paldino's help, which is listed
below...
My code worked well in VS2003. I am now transfering the code into C#
Express, which has a new SerialPort class in it. I came across another
problem this time. My code is also listed below. I would appreciate your
comments.

/******* Your previous answer to my inquiry ********/
Haluk,

When you set the output like this:

com.Output = ((char) 34) + ((char) 14);

You are actually sending a (char) type, not a string, which is what
you really want to send. To do this, do the following:

com.Output = new string(new char[]{(char) 34, (char) 14});

This will create a new string composed of the two characters that
will be marshaled correctly to the COM object.

Also, I suspect that the output stops when it hits the null
character. To get around this, you will have to send the byte manually.

Hope this helps.

--
- Nicholas Paldino [.NET MVP]
- ni************* *@xxxxxxxxxx.co m
"Haluk" <xxxxxxxxxxxxxx > wrote in message
news:b03001c20e 13$606eb230$37e f2ecf@TKMSFTNGX A13...

I am using mscommlib.ocx in my C# application to
communicate via the serial port.
After all the initialization code which I had already used
in my previous VB6 applications successfully, I am using
the following code to transmit data:

com.Output = ((char) 34)+ ((char) 14);

I am getting the following error code when I run this
program:

An unhandled exception of
type 'System.Runtime .InteropService s.COMException'
occurred in axinterop.mscom mlib.dll
Additional information: Exception from HRESULT: 0x800A017C
(CTL_E_INVALIDP ROPERTYVALUE).

But also if I write the same code as follows:

com.Output = "" + ((char) 34)+ ((char) 14);

It runs successfully.
This is my first problem...

The second one is: instead of '34' or '14', for example if
I decide to send '0' (zero), this character is not transmitted at all!
com.Output = "" + ((char) 34)+ ((char) 0);

I can only achieve to transmit '34', but not '0' when I
run this code..

Any explanation will be deeply appreciated..

Regards,
Haluk

/******* My new code in C# (Express) *************** ***/

After the usual port initialization,

if (com.IsOpen) com.Close();
com.Open();

// send char 34,14,192,51,0, 0
com.Write(new string(new char[] { (char)34, (char)14, (char)192,
(char)51, (char)0, (char)0 }, 0, 6));

// for testing purposes I connected TX and RX pins of the port...

// receive routine:
private void com_DataReceive d(object sender, SerialDataRecei vedEventArgs
e)
{

// This method will be called when there is data waiting in the port's
buffer

// Obtain the number of bytes waiting in the port's buffer
bytes = com.BytesToRead ;

// Create a byte array buffer to hold the incoming data
buffer = new char[bytes];

// Read the data from the port and store it in our buffer
com.Read(buffer , 0, bytes);

}
/****** My question about this new code *******/
After I activate the send routine, 6 bytes of data is received by pc but
with some difference to the originally sent data.

I receive : 34,14,63,51,0,0 everytime instead of 34,14,192,51,0, 0

I tried to transmit 34,14,127,51,0, 0 and received the same data
sequence...

As I try to tranmit anything bigger than 127 I receive 63 instead of the
original data...

Do you have any idea why this happens?
Best Regards,
Haluk
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