serialPort receive problem

17 Jun 2009 7:46 AM

tzhumi

Hi all,

I have a class that creates an instance of the seril Port.
Every thing works fine except whenever I receive data I cannot display
the
recieved data. I get no errors but the recived data seems to be empty.
when I try to display it in a text box nothing happens.
I have socket stuff in the same class and it's recieve callbacks work
just
fine and displays just fine.

Here is my code:

Sub OpenComPort()
        Try

            If Not SerialPort1.IsOpen Then
                SerialPort1.PortName = cmbPorts.SelectedItem.ToString

                If cmbBitRate.SelectedIndex > 0 Then
                    SerialPort1.BaudRate = CInt
(cmbBitRate.SelectedItem)
                End If

                SerialPort1.Parity = Parity.None
                SerialPort1.DataBits = 8
                SerialPort1.StopBits = StopBits.One
                SerialPort1.Handshake = Handshake.None
                SerialPort1.Open()

            End If

        Catch ex As Exception
            MessageBox.Show(ex.Message)

        End Try
    End Sub

Private Sub btnOn_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles btnOn.Click
        SendCommand("I2" + eot)
End Sub

Private Sub SendCommand(ByVal command As String)

               Dim response As String = ""
                SerialPort1.Write(command)
                response = SerialPort1.ReadExisting
                textbox1.text=response
End sub

When I send the command the controller responds to the command and it
should return the response by some ascii characters. But I am unable
to display the response from it...Thank you for any help

17 Jun 2009 8:39 AM

James Hahn

The ReadExisting method will return whatever data is available at the serial
port. If nothing is displayed then you should assume that nothing was
available. That would be expected, as the serial port data could not have
been transmitted, and a response received, in the time that you have allowed
between the Write command and the ReadExisting call.

Data will be available at the serial port if the BytesToRead function
returns a positive value. You should call ReadExisting only after
confirming that there are bytes to be read, or following a DataReceived
event.

Show quoteHide quote

"tzhumi" <fren***@googlemail.com> wrote in message
news:f732599c-4d3e-48bb-9888-678782754a2a@w3g2000yqf.googlegroups.com...
> Hi all,
>
> I have a class that creates an instance of the seril Port.
> Every thing works fine except whenever I receive data I cannot display
> the
> recieved data. I get no errors but the recived data seems to be empty.
> when I try to display it in a text box nothing happens.
> I have socket stuff in the same class and it's recieve callbacks work
> just
> fine and displays just fine.
>
> Here is my code:
>
> Sub OpenComPort()
>        Try
>
>            If Not SerialPort1.IsOpen Then
>                SerialPort1.PortName = cmbPorts.SelectedItem.ToString
>
>                If cmbBitRate.SelectedIndex > 0 Then
>                    SerialPort1.BaudRate = CInt
> (cmbBitRate.SelectedItem)
>                End If
>
>                SerialPort1.Parity = Parity.None
>                SerialPort1.DataBits = 8
>                SerialPort1.StopBits = StopBits.One
>                SerialPort1.Handshake = Handshake.None
>                SerialPort1.Open()
>
>            End If
>
>        Catch ex As Exception
>            MessageBox.Show(ex.Message)
>
>        End Try
>    End Sub
>
> Private Sub btnOn_Click(ByVal sender As System.Object, ByVal e As
> System.EventArgs) Handles btnOn.Click
>        SendCommand("I2" + eot)
> End Sub
>
> Private Sub SendCommand(ByVal command As String)
>
>               Dim response As String = ""
>                SerialPort1.Write(command)
>                response = SerialPort1.ReadExisting
>                textbox1.text=response
> End sub
>
> When I send the command the controller responds to the command and it
> should return the response by some ascii characters. But I am unable
> to display the response from it...Thank you for any help

17 Jun 2009 8:47 AM

Mike

tzhumi wrote:

> Hi all,
>
> Private Sub btnOn_Click(ByVal sender As System.Object, ByVal e As
> System.EventArgs) Handles btnOn.Click
> SendCommand("I2" + eot)
> End Sub
>
>
> When I send the command the controller responds to the command and it
> should return the response by some ascii characters. But I am unable
> to display the response from it...Thank you for any help

What is "I2"?

What is "eot"

Looks like an AT I# command. If so, there are 2-3 things here
possible to consider:

1) Send "ATI2"

2) If EOT is not <CR>, than send "ATI2"+chr(13)

3) The move might not be an VERBOSE response mode and needs to be
initialized. To see responses, the standard initialization for all
HAYES AT command set compatible modems are:

ATQ0V1X4

See http://en.wikipedia.org/wiki/Hayes_command_set

--

17 Jun 2009 11:02 AM

fren4uu@googlemail.com

On Jun 17, 10:47 am, Mike <unkn***@unknown.tv> wrote:
Show quoteHide quote

> tzhumi wrote:
> > Hi all,
>
> > Private Sub btnOn_Click(ByVal sender As System.Object, ByVal e As
> > System.EventArgs) Handles btnOn.Click
> > SendCommand("I2" + eot)
> > End Sub
>
> > When I send the command the controller responds to the command and it
> > should return the response by some ascii characters. But I am unable
> > to display the response from it...Thank you for any help
>
> What is "I2"?
>
> What is "eot"
>
> Looks like an AT I# command. If so, there are 2-3 things here
> possible to consider:
>
> 1) Send "ATI2"
>
> 2) If EOT is not <CR>, than send "ATI2"+chr(13)
>
> 3) The move might not be an VERBOSE response mode and needs to be
> initialized. To see responses, the standard initialization for all
> HAYES AT command set compatible modems are:
>
> ATQ0V1X4
>
> Seehttp://en.wikipedia.org/wiki/Hayes_command_set
>
> --

They are the commands for our controller
When I send that command it will give the response...

17 Jun 2009 4:37 PM

Dick Grier

Hi,

You must wait until all data that you need are present. The ReadExisting
method simple reads all data that are available when called -- and nothing
will yet have been received from your device; this code will execute much
faster than the device can respond. You can test for the number of
characters that are available by using the SerialPort.BytesToRead method.

Dick

--
Richard Grier, MVP
Hard & Software
Author of Visual Basic Programmer's Guide to Serial Communications, Fourth
Edition,
ISBN 1-890422-28-2 (391 pages, includes CD-ROM). July 2004, Revised March
2006.
See www.hardandsoftware.net for details and contact information.

23 Jun 2009 1:10 PM

Freddy Coal

Wait a time before read the port, and write commands with end line.

For write is something like:

Private Sub SendCommand(ByVal command As String)
                SerialPort1.Write(command & vbcrlf)
End sub

For read, you can wait a specific time, or read in the event of the Com
port, something like:

Private Sub Serial_Recibir(ByVal sender As System.Object,
    ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) _
    Handles Serial.DataReceived
        Msgbox(Me.Serial.ReadExisting())
End Sub

Try with that, maybe is a good solution for you.

Freddy Coal

Show quoteHide quote

"tzhumi" <fren***@googlemail.com> wrote in message
news:f732599c-4d3e-48bb-9888-678782754a2a@w3g2000yqf.googlegroups.com...
> Hi all,
>
> I have a class that creates an instance of the seril Port.
> Every thing works fine except whenever I receive data I cannot display
> the
> recieved data. I get no errors but the recived data seems to be empty.
> when I try to display it in a text box nothing happens.
> I have socket stuff in the same class and it's recieve callbacks work
> just
> fine and displays just fine.
>
> Here is my code:
>
> Sub OpenComPort()
>        Try
>
>            If Not SerialPort1.IsOpen Then
>                SerialPort1.PortName = cmbPorts.SelectedItem.ToString
>
>                If cmbBitRate.SelectedIndex > 0 Then
>                    SerialPort1.BaudRate = CInt
> (cmbBitRate.SelectedItem)
>                End If
>
>                SerialPort1.Parity = Parity.None
>                SerialPort1.DataBits = 8
>                SerialPort1.StopBits = StopBits.One
>                SerialPort1.Handshake = Handshake.None
>                SerialPort1.Open()
>
>            End If
>
>        Catch ex As Exception
>            MessageBox.Show(ex.Message)
>
>        End Try
>    End Sub
>
> Private Sub btnOn_Click(ByVal sender As System.Object, ByVal e As
> System.EventArgs) Handles btnOn.Click
>        SendCommand("I2" + eot)
> End Sub
>
> Private Sub SendCommand(ByVal command As String)
>
>               Dim response As String = ""
>                SerialPort1.Write(command)
>                response = SerialPort1.ReadExisting
>                textbox1.text=response
> End sub
>
> When I send the command the controller responds to the command and it
> should return the response by some ascii characters. But I am unable
> to display the response from it...Thank you for any help