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In many programs, there is an option for selecting the serial port. Instead of providing selection for all possible ports and building an error handling routine for those non-existed in hardware, here is an easy way to enumerate the serial ports of a computer, using Visual Basic 5 or higher (I am not sure about the older versions). It works on both Win95-98 and Win NT 4.
option Explicit
'*************************************************************
' Module : EnumPorts
' FileName : EnumPorts.BAS
' Author : Dimitrios Papadopoulos
' date Created : 10/08/00 22:07:10
'
' Copyright : 2000, Dimitrios Papadopoulos.
' All Rights Reserved.
'
' Description : Enumerates Existance of COM Ports
'
' Change History :
' 1.0 10 August 2000
' Dimitrios Papadopoulos
' Initial Version
'
'*************************************************************
Type DCB
DCBlength as Long
BaudRate as Long
fBitFields as Long
wReserved as Integer
XonLim as Integer
XoffLim as Integer
ByteSize as Byte
Parity as Byte
StopBits as Byte
XonChar as Byte
XoffChar as Byte
ErrorChar as Byte
EofChar as Byte
EvtChar as Byte
wReserved1 as Integer
End Type
Type COMMCONFIG
dwSize as Long
wVersion as Integer
wReserved as Integer
dcbx as DCB
dwProviderSubType as Long
dwProviderOffset as Long
dwProviderSize as Long
wcProviderData as Byte
End Type
'
Declare Function GetDefaultCommConfig Lib "kernel32" _
Alias "GetDefaultCommConfigA" (byval lpszName as string, _
lpCC as COMMCONFIG, lpdwSize as Long) as Long
'
public Function EnumSerPorts(port as Integer) as Long
'this function returns non-zero value if the port exists
Dim cc as COMMCONFIG, ccsize as Long
'
ccsize = LenB(cc) 'gets the size of COMMCONFIG structure
'
EnumSerPorts = GetDefaultCommConfig("COM" + Trim(Str(port)) + _
Chr(0), cc, ccsize)
'
End Function
