serial port - com

Question

I toke from the VB6 the example about using the serial port with MSComm.
I run this program in VB2005 after it was upgrade ofcourse by the VB2005
and try to send and receive strings in a loop(1-1000).
But sometimes in this loop the string that I'm sending is stuck or something that I don't understand why???

I run this loop with the some strings a lot of times and everytime is a different
string that stuck. if someone can tell me why???

In VB2005 there is something similar to MSComm that I can use??

Answer 1

Hi,

Visual Basic 2005 has a separate SerialPort control which you can use for serial communication.
http://msdn2.microsoft.com/en-us/library/system.io.ports.serialport.aspx

Sample available only in C# - http://www.gotdotnet.com/team/clr/bcl/demos/demos/zipfiles/SerialLCDCS.zip

Regards,
Vikram

Answer 2

Thanks for the quick answer,

But I'm Beginner in VB2005 programming and I be glad if I can get example
of how to add this SerialPort control and how to use like the basic command
as open the SerialPort,write,read and close.

Regards,
yaniv

Answer 3

Hi,

Here's a simpler example - but still in C#.

Let me know if you can figure out, or I will convert it to VB2005 and send it to you:
http://www.codeproject.com/csharp/SerialCommunication.asp

Regards,
Vikram

Answer 4

Hi, thanks again

But I can't figure out how can I use it in VB2005.
I tried to drag "SERIALPORT CONTROL" from the "toolbox" to the "form1.vb(design)"
but after that I didn't know how to apply to this serialport.

If you can convert it to VB2005 it be great

thanking you in advance
yaniv

 

Answer 5

Hi,

You do not even drag drop the control. You can create an instance by declaring a variable of type SerialPort and use that. Anyways, I have that sample converted.

Let me know your email Id so that I can email the project to you.

Regards,
Vikram

Answer 6

I'm really appreciate it...

my email : [e-mail]

thanks again,

yaniv

Answer 7

Hi,

I have e-mailed the sample in VB2005 to you.

Regards,
Vikram

Answer 8

Hi,

Thanks for the files it was very helpful.

I have a little problem that I can't figure out how can I solve it.

I want that my program will work in a loop and check if something come from the serialport or if there a file that another program sent to me.
something like this:

Dim a
Dim i as integer, flag_file as short
i=0
flag_file=0

Do
  If Not (a = Dir("c:\temp.txt")) Then flag_file = 1 
   i = sp.readbyte
loop untill (i>0 or flag_ file=1)


but the problam is that if nothing comming from the serialport it's stuck and wait.
I'm using readbyte and not readline cause I can get chr(0) or enter (asci 0 till asci 255) from the serailport.

there is solution for that ?

thanks again,
yaniv

Answer 9

Hi,
I didn't notice that you use with " try " and "catch" so now it is working as I wanted.

But now  I have another problem I tried to sent chr(129) and I received in the other computer chr(63).

when I sent chr(0) till chr(127) it work fine.

from chr(128) till chr(255) some of them are fine and some of them
I'm getting chr(63)

So how can I fix that?

yaniv

Answer 10

try using chrw(x) instead of chr(x)

Dustin

Answer 11

I tried chrw(x) it's still work the same,

this is how I open the port: (maybe I didn't do something right?)

sp.PortName = "COM1"

sp.ReadTimeout = 500

sp.DtrEnable = True

sp.RtsEnable = True

sp.BaudRate = 19200

sp.DataBits = 8

sp.StopBits = StopBits.One

sp.Parity = Parity.None

sp.Open()

if you have another idea I'll be happy to try....

Answer 12

It looks like his code is looking for eight bit enties and not 16 so I'm really sure that Chrw will not work. My understanding is that these days the chrw chr are both 16 bit entities.

It looks as if the byte high-bit is being used as a sign bit in places.

Answer 13

Hi

I have graduation project that is about RS-232 serial cominication. I am developing my  code with .NET 2005.

I want to control RS-232,

code;

 

private void write_click(object sender, EventArgs e)
{
     if (!serialPort1.IsOpen)
     {
         serialPort1.Open();
     }
     string sendmesaj = textBox1.Text+"-->>>>";
     serialPort1.WriteLine(sendmesaj);
}

private void read_click(object sender, EventArgs e)
{

     string i=serialPort1.ReadLine();
     textBox2.Text ="<<<<---"+i;
     serialPort1.Close();

}

 

when I send data that is ony between 1 and 5 characters, it is ok. However when send characters more than 6 for exmaple "abcdefghi" it is faild.

please help me

thanks a lot

Answer 14

Hi,

Look I'm still a rookie in VB2005 but I'll try to help you...

So I guess that you are trying to connect between two computers.
and you have problem with sending characters but, I'm thinking that the problem
is receiving the characters on the other computer.

You need to know how many characters (or till when?) to receive from the serial port otherwise after you sent the characters that you want,
the receiveing computer will still wait for more data till time out will appear.

When I wrote a similar program in VB2005 I had a problem that I sent char(13) (as you know that equal to end of line) and I receive on the other computer chr(129).

that mean that the receiving computer didn't know that was the end of the line and wait for more data.

So I worked differently I read the first byte that tell me how many bytes I need to receive. and then I know when to stop receiving characters.

But then again I'm not sure that is the same problem in your program...

Hope that I help you some how.....

Regards,

Yaniv

 

 

Answer 15

hellow

 

is it possible to mail the converted version of the serial communications also to me ?

I have the same problem with the vb2005.

 

many greetings , sierjacobs, ghent, belgium

Answer 16

Hi!

 

I'm trying to make a project that consists in communicate an hp IPAQ hx 2700 with serial port to my pc. This Ipaq works with windows mobile 5.0.  I communicated them by making an application in vb 2005 for the pda and communicating with the hyperterminal in the pc. I'm having troubles because i can write things in the pda to the pc, but i can't write things in the pc and view them on the pda.

 

I think that maybe i have to add a library or i have to configure some propierties, but i dont know what to do. Here's the code i used:

 

Imports System.IO.Ports.SerialPort

Public Class Form1

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

SerialPort1.Open()

End Sub

Private Sub CmdEnviar_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CmdEnviar.Click

SerialPort1.WriteLine(TxtTX.Text)

TxtTX.Text = ""

End Sub

Private Sub DataReceived(ByVal sender As System.Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived

Dim Returnstr As String = ""

Do

Dim Incoming As String = SerialPort1.ReadExisting

If Incoming Is Nothing Then

Exit Do

Else

Returnstr &= Incoming & vbCrLf

End If

Loop

TxtRX.Text = TxtRX.Text + Returnstr

End Sub

Private Sub MenuItem1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MenuItem1.Click

Application.Exit()

End Sub

Private Sub Form1_Close()

SerialPort1.Close()

End Sub

End Class

 

The propierties i used in the serial port are:

 

Name: SerialPort1

Generate Member: True

Modifiers: Friend

Baud Rate: 9600

Data bits: 8

Discard Null: False

DTR Enable: True

Handshake: None

Parity: None

Parity replace: 63

Port Name: COM 1

ReadBufferSize: 4096

Read Timeout: -1

Received bytes threshold: 1

RTS Enable: True

Stop bits: 1

Write buffer size: 2048

Write timeout: -1

 

Hope you can help me please.....

 

Thank you VERY MUCH!!!!!

 

Lina