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Receiving ASKEY through the Serial port

Posted on 2003-03-04
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Last Modified: 2010-05-01
I have new covered receiving information through the RS232 port so this is probably really simple but I need some help.

I have a device that sends an askey value (Time taken from a stopwatch) to the Rs232 port. I want to load this information into a VB program so that I can calculate the speed the object is going.

So how do you capture this information from a RS232 port, and place in a variable?
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Question by:neeveser
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4 Comments
 
LVL 3

Accepted Solution

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PNJ earned 200 total points
ID: 8065550
Use MSCOMM32.OCX and place a control onto the form. Set the properties to the correct baud rate and start/stop bit etc. either in code or at design time.

Here's a few code fragments to get you going. This is taken from our crane control system:

in form load:
   SetUpPort

Private Sub comWatch_OnComm()
   
   Dim Temp As String

   Select Case comWatch.CommEvent
   Case comEvReceive ' Received RThreshold # of chars.
   
      ' Grab the string/character
      Temp = GetInputBuffer(vbNullString, comA)
     
   Case Else

      Temp = "Unknown Event/Error"
      Log Me, LOG_MESSAGE, Temp

   End Select

End Sub

Function GetInputBuffer(Routine As String, ComPort As MSComm) As String

   Dim Temp As Variant, i As Integer, Message As String
   Dim AChar As Integer
     
   ' Read the Comm Port input buffer, flush it, and log the data received
   
   ' Return the data as a string
   GetInputBuffer = vbNullString
   
   If ComPort.InBufferCount = 0 Then Exit Function ' Nothing in input buffer
   
   Temp = vbNullString
   
   Do While ComPort.InBufferCount > 0
   
      Temp = Temp & ComPort.Input
     
      Message = vbNullString
      For i = 1 To Len(Temp)
         AChar = Asc(Mid$(Temp, i, i))
         Message = Message & IIf(AChar >= 32, Chr$(AChar), "[&H" & Hex(AChar) & "]")
      Next i
     
      If Routine <> vbNullString Then
         Log Me, LOG_MESSAGE, "From " & Routine & ". Data: " & Message
      End If
     
   Loop

   GetInputBuffer = Temp
   
End Function
Sub SetUpPort()

   On Error GoTo SetUpErr
     
   With comWatch
   
      .Handshaking = comNone
      .InputMode = comInputModeText
      ' Use COM3 as default
      .CommPort = 3
      ' Use 1200 baud, even parity, 8 data, and 1 stop bit as default.
      .Settings = "1200,E,8,1"
     
      .InputLen = 0            ' Tell the control to read entire buffer when Input
                               ' is used.
      .PortOpen = True         ' Open the port.
      .InputLen = 0            ' Read all of the text
      .RThreshold = 1          ' Interrupt every character
     
   End With
   
   Exit Sub
   
SetUpErr:
   If Err = 8005 Then Resume Next ' Port aleady open
   FatalADOError Err.Number, Err.Description, "SetUpPort", Me.Caption
End Sub
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LVL 3

Expert Comment

by:PNJ
ID: 8065559
...sorry, you'll need to close it on form exit:

 comWatch.PortOpen = False  
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LVL 49

Expert Comment

by:DanRollins
ID: 9024176
Hi neeveser,
It appears that you have forgotten to close this question. I will ask Community Support to close it unless you finalize it within 7 days. I will ask a Community Support Moderator to:

    Accept PNJ's comment(s) as an answer.

neeveser, if you think your question was not answered at all or if you need help, just post a new comment here; Community Support will help you.  DO NOT accept THIS comment as an answer.
==========
DanRollins -- EE database cleanup volunteer
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