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How to open and read from multiple serial ports at the same time

How to open and read from multiple serial ports at the same time

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Noora	12 Oct, 2008 - 07:21 AM Post #1
New D.I.C Head Joined: 12 Oct, 2008 Posts: 8	I’m a beginner in vb.net and I have no knowledge in it, but I have to use it to do my project. I found a tutorial about Serial Port Communication in VB.Net develped by Psychocoder it was very helpful. I tested the code, it works great to open and read from one comport, but unfortunately when I tried to modify the code to open all the available comports in the system by adding a loop to get all available ports and read from them simultaneously it doesn’t work well!! In The open port method, it opens the first available port and when it gets the second it closes the opened one and then opens the next port and so on. I modify this sub routine in the frmMain class: CODE Private Sub cmdOpen_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdOpen.Click comm.Parity = cboParity.Text comm.StopBits = cboStop.Text comm.DataBits = cboData.Text comm.BaudRate = cboBaud.Text comm.DisplayWindow = rtbDisplay ''''''''''''''''''''''''''''''''''''''''''''''''' ''These lines I add in the code: For Each str As String In SerialPort.GetPortNames() comm.PortName = str comm.OpenPort() Next str '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' cmdOpen.Enabled = False cmdClose.Enabled = True cmdSend.Enabled = True End Sub I tried to check where is the fault, so I tried to remove the command that close the opened port but still it doesn’t work, another issue I faced, only one port is opened. In the CommManager class: CODE Public Function OpenPort() As Boolean Try 'first check if the port is already open 'if its open then close it ''I removed these lines that close the opened port before openning the next one : If comPort.IsOpen = True Then comPort.Close() End If How can I open all available ports at the same time and read from them as well???? Do I have to change the whole code?? Or maybe use another library by importing it?? Or is it possible to use the same program and modify it?? Thank you and waiting for a help soon
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Noora	RE: How To Open And Read From Multiple Serial Ports At The Same Time 18 Oct, 2008 - 11:53 AM Post #2
New D.I.C Head Joined: 12 Oct, 2008 Posts: 8	Help!! Anyone!!!!!
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dbasnett	RE: How To Open And Read From Multiple Serial Ports At The Same Time 18 Oct, 2008 - 03:31 PM Post #3
D.I.C Head Joined: 1 Oct, 2008 Posts: 161 Thanked: 5 times My Contributions	CODE 'open all the ports Dim comm As New List(Of IO.Ports.SerialPort) 'list of comm ports For Each PNstr As String In IO.Ports.SerialPort.GetPortNames() 'get a list of Com Port Names comm.Add(New IO.Ports.SerialPort) 'insert new port into list comm(comm.Count - 1).PortName = PNstr 'set the name 'set other items code here Try comm(comm.Count - 1).Open() 'open it If Not (comm(comm.Count - 1).IsOpen) Then 'did it really open comm.RemoveAt(comm.Count - 1) 'no, remove from list Else Debug.WriteLine(comm(comm.Count - 1).PortName & " opened") End If Catch End Try Next PNstr For z As Integer = 0 To comm.Count - 1 'close em Try Debug.WriteLine(comm(z).PortName & " closed") If comm(z).IsOpen Then comm(z).Close() 'close it Catch End Try Next This post has been edited by dbasnett: 18 Oct, 2008 - 03:45 PM
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Noora	RE: How To Open And Read From Multiple Serial Ports At The Same Time 20 Oct, 2008 - 02:02 AM Post #4
New D.I.C Head Joined: 12 Oct, 2008 Posts: 8	Thanks dbasnett the code was helpful But I didn't understand why do you write the lines that close the ports after opening them?! I need to keep all the ports open to read from all of them all the time, when I remove these lines all the ports open successfully but still can't read or receive data from any one of them!! can you help me in that also CODE For z As Integer = 0 To comm.Count - 1 'close em Try Debug.WriteLine(comm(z).PortName & " closed") If comm(z).IsOpen Then comm(z).Close() 'close it Catch End Try Please I need your help, I work in a project deals with RFID Readers and tags, I just recently learn how to program using vb.net to do this project
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dbasnett	RE: How To Open And Read From Multiple Serial Ports At The Same Time 20 Oct, 2008 - 02:45 AM Post #5
D.I.C Head Joined: 1 Oct, 2008 Posts: 161 Thanked: 5 times My Contributions	i closed them as an example, and because they should be closed when finished using them. how often do you have to read from the RFID readers? let me be frank. there are a lot of experienced VB programmers that have difficulties reading / writing to one serial port properly. here SerialPort is an example of a project I did that reads one port. it should not be used in a commercial application!
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Noora	RE: How To Open And Read From Multiple Serial Ports At The Same Time 20 Oct, 2008 - 12:08 PM Post #6
New D.I.C Head Joined: 12 Oct, 2008 Posts: 8	When a tag passes near to one of the RFID readers that connected to computer serial ports (including the virtual comports), I have to receive the Tag ID and then store it in an access database , that's why I have to keep all the ports open all the time please I need your help also in reading from all the serial ports
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magicmonkey

RE: How To Open And Read From Multiple Serial Ports At The Same Time
20 Oct, 2008 - 12:59 PM

Post #7

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Joined: 12 Sep, 2008
Posts: 413

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My Contributions

Maybe this can get you started??? It is based on dbnasnet post but I added an event handler for datareceived and seperated the open and close routines.


  Private MonitorSP As New List(Of IO.Ports.SerialPort)

    Private Sub OpenSP()
        CloseSP()

        For Each PortName As String In IO.Ports.SerialPort.GetPortNames()
            Try
                Dim newSP As New IO.Ports.SerialPort(PortName)
                newSP.Open()
                If newSP.IsOpen Then
                    AddHandler newSP.DataReceived, AddressOf MonitorSP_DataReceived
                    MonitorSP.Add(newSP)
                End If
            Catch ex As Exception
                'Failed
            End Try
        Next
    End Sub

    Private Sub CloseSP()
        For Each selSP As IO.Ports.SerialPort In MonitorSP
            selSP.Close()
        Next
        MonitorSP.Clear()
    End Sub

    Private Sub MonitorSP_DataReceived(ByVal sender As Object, ByVal e As IO.Ports.SerialDataReceivedEventArgs)
        Dim SP As IO.Ports.SerialPort = DirectCast(sender, IO.Ports.SerialPort)
        Dim Data As String = SP.ReadLine
        'Remember this is in a background thread so you can not update the UI from here without using Me.Invoke
    End Sub

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dbasnett	RE: How To Open And Read From Multiple Serial Ports At The Same Time 20 Oct, 2008 - 02:47 PM Post #8
D.I.C Head Joined: 1 Oct, 2008 Posts: 161 Thanked: 5 times My Contributions	what is the format of the data?
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Noora	RE: How To Open And Read From Multiple Serial Ports At The Same Time 21 Oct, 2008 - 03:27 AM Post #9
New D.I.C Head Joined: 12 Oct, 2008 Posts: 8	The data format is ASCII but i have to convert it to text format
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dbasnett	RE: How To Open And Read From Multiple Serial Ports At The Same Time 21 Oct, 2008 - 05:04 AM Post #10
D.I.C Head Joined: 1 Oct, 2008 Posts: 161 Thanked: 5 times My Contributions	i meant the protocol like this (BTW - byte = char) <byte 1><byte 2><byte 3><byte 4>....<byte x> example: byte 1 = byte 2 -3 = byte 4 = byte 5-8 =
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Noora	RE: How To Open And Read From Multiple Serial Ports At The Same Time 22 Oct, 2008 - 07:37 AM Post #11
New D.I.C Head Joined: 12 Oct, 2008 Posts: 8	I don't know the format for the received data, I have to ask the company that I bought the RFID readers from Thanks dbasnett and magicmonkey your both codes help me alot in my project I'm now able to open and read from multiple serial ports at the same time
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