I had a letter asking me how can you return the number of Data-Bits, Stop-Bits and the parity of a specified port, i.e. the Communications port in which your modem is connected to.

This can be simply done using the CreateFile API to open up the port and then the GetCommState API to query information about the COM port.

Below is an example showing you how you can receive these three properties.

There are actually more that you can return like the baud rate and more.

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

Const NOPARITY = 0

Const ODDPARITY = 1

Const EVENPARITY = 2

Const MARKPARITY = 3

Const SPACEPARITY = 4

Const ONESTOPBIT = 0

Const ONE5STOPBITS = 1

Const TWOSTOPBITS = 2

Declare Function GetCommState Lib "kernel32" (ByVal nCid As Long, lpDCB As

DCB) As Long

Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" (ByVal

lpFileName As String, _

ByVal dwDesiredAccess As Long, ByVal dwShareMode As Long, ByVal

lpSecurityAttributes As Long, _ ByVal dwCreationDisposition As Long, ByVal

dwFlagsAndAttributes As Long, ByVal hTemplateFile _ As Long) As Long

Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long

Dim tDCB As DCB

Function GetPortInfo(sCommPort As String) As Long

Dim lHandle As Long, RetVal As Long

lHandle = CreateFile(sCommPort, &HC0000000, 0, 0, 3, 0, 0)

If lHandle = -1 Then GetPortInfo = 0: Exit Function

Call GetCommState(lHandle, tDCB)

lHandle = CloseHandle(lHandle)

With tDCB

Debug.Print "--- Properties ---"

Debug.Print "Data Bits: " & .ByteSize

Select Case .Parity

Case NOPARITY: Debug.Print "Parity: No Parity"

Case ODDPARITY: Debug.Print "Parity: Odd"

Case EVENPARITY: Debug.Print "Parity: Even"

Case MARKPARITY: Debug.Print "Parity: Mark"

Case SPACEPARITY: Debug.Print "Parity: Space"

End Select

Select Case .StopBits

Case ONESTOPBIT: Debug.Print "Stop Bits: 1"

Case ONE5STOPBITS: Debug.Print "Stop Bits 1 1/2"

Case TWOSTOPBITS: Debug.Print "Stop Bits: 2"

End Select

End With

GetPortInfo = 1

Call the function like the following