Private Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" (ByVal lpFileName As String, ByVal dwDesiredAccess As Long, ByVal dwShareMode As Long, lpSecurityAttributes As SECURITY_ATTRIBUTES, ByVal dwCreationDisposition As Long, ByVal dwFlagsAndAttributes As Long, ByVal hTemplateFile As Long) As Long

Private Declare Function ReadFile Lib "kernel32" Alias "ReadFile" (ByVal hFile As Long, lpBuffer As Any, ByVal nNumberOfBytesToRead As Long, lpNumberOfBytesRead As Long, lpOverlapped As OVERLAPPED) As Long

Private Declare Function WriteFile Lib "kernel32" Alias "WriteFile" (ByVal hFile As Long, lpBuffer As Any, ByVal nNumberOfBytesToWrite As Long, lpNumberOfBytesWritten As Long, lpOverlapped As OVERLAPPED) As Long

 

Const FILE_ATTRIBUTE_TEMPORARY = &H100

Const OPEN_EXISTING = 3

Const GENERIC_READ = &H80000000

Const GENERIC_WRITE = &H40000000

 

 

......

dim a as byte

ComPort="\.\COM25"

hComm=CreateFile(ComPort, GENERIC_READ or GENERIC_WRITE, 0, 0,OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0)

 

ReadFile hComm,a,1, 1,byval &0

WriteFile hComm,a,1,1,byval &0