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MSCOMM

Posted on 2004-08-17
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Last Modified: 2013-12-25
Hello,
I have a vb program where I let the user enter a com port number that they will be using for an rs232 device.
It works well.

If I try to open a comport that I do not have
(com port 4) it gives me an error that says
 invalid com port number.


   MSComm1.CommPort = myComPortNumber
   MSComm1.InputLen = 0
   MSComm1.Settings = "9600,N,8,1"
   MSComm1.PortOpen = True


How do I test for this before the error happens?
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Question by:jackjohnson44
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1 Comment
 
LVL 11

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bingie earned 125 total points
ID: 11825301
Try this function

Private Function DoesCommPortExist(CommPort As Integer) As Boolean
On Error Resume Next
        MSComm1.CommPort = CommPort
        MSComm1.PortOpen = True
        If Not (Err.Number = 8002) Then  
            MsgBox "CommPort Exists"
            DoesCommPortExist = True
        Else
            MsgBox "CommPort Does Not Exist"
            DoesCommPortExist = False
        End If
        MSComm1.PortOpen = False
End Function


Just pass the comm port number you wish to test with the following:

x = DoesCommPortExist (comm port number)

It will return a boolean true / false based on the result. You can then comment out the msgboxes.

Bingie
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