Control.com - Nerds in Control

The easiest way to access COM ports in Visual Basic 6 is by placing the Microsoft Comm control on a form, and writing code to read and write each serial port. There are plenty of examples on the web of using the Microsoft Comm control to send and recieve data from a serial port. You will need one Microsoft Comm control on your form per serial ports you wish to use.

Example of an infinite loop that takes data from one port and echos it onto another -

Dim sInput as String
While (True)
    DoEvents
    sInput = MSComm1.Input
    If (Len(sInput) > 0) Then
        MSComm2.Output = sInput
    End If
Wend

1- go to "project" menu<br>
2- select "components"<br>
3- on control tab click the check box of "Microsoft Comm control 6.0"<br>
4- u will see a sign of telephone on General where u can find out text box, label, etc.<br>
5- select that MSCOMM control object and drag and drop on your Form1.<br>
6-double click on form1.<br>
7-copy & paste the following code:<br>

Private Sub Form_Load()
 

   com1.CommPort = 2  ' comm port no.
   com1.Settings = "1200,e,7,2"
   com1.RThreshold = 24    'no. of chr to recive
   com1.InputLen = 0  '  no. of chr on which oncomm  event fires
    
   com1.PortOpen = True  'open comm port

End Sub



Public Sub Com1_OnComm()
    Dim txtBuf
    Dim i As Integer
    Dim c As Integer
    Dim buffer
    Dim stable
    Dim EVMsg$
    Dim ERMsg$
    buffer = ""
    txtweight.Text = ""
    With com1
    
        Select Case .CommEvent
            Case comEvReceive
                buffer = .Input
                For i = 1 To Len(txtBuf)
                    c = Asc(Mid$(txtBuf, i, 1))
                    If (c < 32 Or c > 126) Then
       txtweight = txtweight & "" & Hex(c) & ""
                    Else
                  txtweight = txtweight & Chr(c)
                    End If
                       
              Next i
   '***************************************************************
   
        ' Error messages.
        Case comBreak
            ERMsg$ = "Break Received"
        
        Case comFrame
            ERMsg$ = "Framing Error"
        Case comOverrun
            ERMsg$ = "Overrun Error"
        Case comRxOver
            ERMsg$ = "Receive Buffer Overflow"
        Case comRxParity
            ERMsg$ = "Parity Error"
         
        Case Else
            ERMsg$ = "Unknown error or event"
   '***************************************************************
        End Select
  
End Sub

9- if any problem contact me, tell me how many char u want to tx/rx.

Sir,

I am trying to write some data @ com1 and read the same data. Here is my sample code. But I could not send or receive and data.

What ever data I send is in txt_tx box and the receive data should be ib txt_rtx box.

Private Sub cmdexit_Click()
End
End Sub


Private Sub cmdtrigger_Click()

Dim i, j As Integer

i = MSComm1.OutBufferCount
MsgBox i

j = MSComm1.InBufferCount
MsgBox j

End Sub

Private Sub Form_KeyPress(KeyAscii As Integer)

MSComm1.SThreshold = 1

MSComm1.Output = KeyAscii
txt_tx.Text = KeyAscii

MSComm1.RThreshold = 1

End Sub

Private Sub Form_Load()

MSComm1.CommPort = 1             'Use com1 port
MSComm1.Settings = "38400,N,8,1" 'Port Settings

MSComm1.InputLen = 0             'Read entire Rx Buffer
MSComm1.PortOpen = True         'open port

End Sub


Private Sub MSComm1_OnComm()

If MSComm1.CommEvent = comEvReceive Then
        txt_rx.Text = MSComm1.Input
Else
    MsgBox "Sorry No Data In Rx Buffer"

End If

End Sub

hi,

i'm working on a project that transfer a text data between two computer and use the following code:

 Private Sub cmdExit_Click()
End
End Sub

Private Sub cmdReceive_Click()
If (Len(txtReceive) > 0) Then
  txtReceive = vbNullString
  txtReceive.Text = MSComm1.Input
End Sub

Private Sub cmdSend_Click()
If (Len(txtSend) > 0) Then ' make sure that there is text to send
        If (MSComm1.PortOpen = True) Then ' make sure the serial port was initialized
            ' send the text as well as a carriage return and line feed appended to the end
            MSComm1.Output = txtSend & vbCr & vbLf
        Else
            MsgBox "ERROR: serial port not initialized"
        End If
    Else
        MsgBox "ERROR: there is no text to send"
    End If
    ' after sending clear the text out of the input box
    txtSend = vbNullString
End Sub

Private Sub cmdStart_Click()

    MSComm1.CommPort = 1
    ' MSComm1.CommPort = 1
    ' 9600 baud, no parity, 8 data, and 1 stop bit.
    MSComm1.Settings = "9600,N,8,1"
    ' Tell the control to read entire buffer when Input is used
    MSComm1.InputLen = 0
    ' generate an event on every character received
    MSComm1.RThreshold = 1
    ' Open the port.
    MSComm1.PortOpen = True
    ' Note: we should set the multiline property to True here in code but it is a read-only property
    ' do not allow the user to change the received text
    txtReceive.Locked = True
    ' clear the intial text boxes
    txtReceive.Text = vbNullString
    ' Send the attention command to the modem.
    InputData = ""
End Sub

Private Sub MSComm1_OnComm()
 Dim InputData As String
    
    Select Case MSComm1.CommEvent

   ' Errors
        Case comEventBreak   ' A Break was received.
            MsgBox "Break received"
        Case comEventFrame   ' Framing Error
            MsgBox "Framing error"
        Case comEventOverrun   ' Data Lost.
            MsgBox "Overrun error"
        Case comEventRxOver   ' Receive buffer overflow.
            MsgBox "Receive Buffer overflow"
        Case comEventRxParity   ' Parity Error.
            MsgBox "Parity Error"
        Case comEventTxFull   ' Transmit buffer full.
            MsgBox "Transmit Buffer full"
        Case comEventDCB   ' Unexpected error retrieving DCB
            MsgBox "DCB error"

   ' Events
        Case comEvCD   ' Change in the CD line.
            MsgBox "Carrier Detect changed state"
        
        Case comEvDSR   ' Change in the DSR line.
            MsgBox "Data Set Ready (DSR) changed state"
        Case comEvRing   ' Change in the Ring Indicator.
            MsgBox "Ring Indicator (RI) changed state"
        Case comEvReceive   ' Received RThreshold # of characters
         '    MsgBox Str$(MSComm1.RThreshold) & " Characters received"
         '   While (MSComm1.InBufferCount > 0)
           '     txtReceive = txtReceive & MSComm1.Input
                ' only keep the last 5,000 characters -- throw away any characters older than that
            '    txtReceive = Right$(txtReceive, 5000)
           ' Wend
           
       InputData = InputData + MSComm1.Input
       Case comEvCTS       ' Change in the CTS line.
       MsgBox "Clear To Send (CTS) changed state"
       ReceivedDataTextBox.Text = InputData
       InputData = ""

        Case comEvSend   ' There are SThreshold number of characters in the transmit buffer
            MsgBox Str$(MSComm1.SThreshold) & " Characters remaining in transmit buffer"
        Case comEvEOF   ' An EOF charater was found in the input stream
            MsgBox "EOF received"
    End Select
End Sub
*****************************************

but i couldn't recieve any character.
Can any one help me in correcting this code.
if there is any contact me with the ff address.<br>
abelmesay97@yahoo.com

thank you!

I would not recommend using infinite loops, instead use the MSComm event.

Private Sub MSComm1_OnComm()

Dim strInput As String
Dim intInput As Integer
Const intMax As Integer = 150

    strInput = MSComm1.Input
    ' Locate the value you are interested in within the input string
    ' in this example it is the last three characters, which we convert to an integer
    intInput = CInt(Right(strInput, 3))
    If intInput > intMax Then
        MsgBox strInput & " is too large, please make it smaller!"
    End If

End Sub

Neil Kingston<br>
Data Layers

Connecting processes with IT<br>
http://www.opcware.com

Hi

i want to pass a particular word on my form to be display as a label i have this code is there any way i can tell if the word is right, and been received by displaying the word. i can see the word lama. but no labe display on form

Option Explicit

Private Sub Form_Load()

 Dim Buffer As String
   ' Buffer to hold input string
   Dim Instring As String
   ' Use COM1.
   MSComm1.CommPort = 1
   ' 9600 baud, no parity, 8 data, and 1 stop bit.
   MSComm1.Settings = "9600,N,8,1"
   ' Tell the control to read entire buffer when Input
   ' is used.
   MSComm1.InputLen = 0
   ' Open the port.
  MSComm1.PortOpen = True
   
    ' Send the attention command to the modem.
   MSComm1.Output = "lama " & vbCr   ' Ensure that
   ' the modem responds with "OK".
   ' Wait for data to come back to the serial port.
    
 Buffer$ = Buffer$ & MSComm1.Input
If InStr(Buffer$, "Test") Then

 Label1.Caption = "OEM4 Detected"
 
 End If

   End Sub

Hi,

The serial port takes in a binary number i.e 1010, I want VB to take the binary word and based on the number received, it will display an alert in a msgbox or a label. Could some help me with the code that lets the serial port input this data to VB and store it in some sort of variable. This is the code I have, and i am not sure if it is right.

Private Sub Form_Load()
    
    frmVSS.Top = (Screen.Height - frmVSS.Height) / 2
    frmVSS.Left = (Screen.Width - frmVSS.Width) / 2
    com1.CommPort = 1  'comm port no.
    com1.Settings = "4800,N,8,1" 'Port Settings
    com1.RThreshold = 4    'no. of characters to receive
    com1.InputLen = 4  'no. of binary characters on which oncomm event fires
    com1.PortOpen = True  'open comm port
   
End Sub

Any help is greatly appreciated.

I am trying to use two serial ports (and perhaps more) on the same form with VB6, I have no problems getting one MSComm event defined and working but when I try to add the second I get a "duplicate Definition" error. Any ideas as to why this wont work for me?

This code works great:

Dim WithEvents MSCommRatio1 As MSCommLib.MSComm

Private Sub Form_Open(Cancel As Integer)
    'code to load the form and 
    'set up the comm     
    'port,
End Sub


Private Sub MSCommRatio1_OnComm()
    'code to read the port at the correct time. 
    'and put the data were I want it
End Sub

This code gives the error:

Dim WithEvents MSCommRatio1 As MSCommLib.MSComm
Dim WithEvents MSCommRatio2 As MSCommLib.MSComm

Private Sub Form_Open(Cancel As Integer)
    'code to load the form and set up 
    'the comm objects on two different ports
End Sub


Private Sub MSCommRatio1_OnComm()
    'code to read the port at the correct time. 
    'and put the data were I want it
End Sub

Private Sub MSCommRatio2_OnComm()
    'code to read the port at the correct time. 
    'and put the data were I want it
End Sub