How to determine if a serial port is present or not

[CountyIT]

I have a function to determine if a serial port exists on a computer or not. I am working with virtual serial ports and as a result it could actually disappear (the user pulls the USB cable) and re-appear quite often. As a result I need to continue to monitor for the presece (or absense) of this serial port. The one I have (below) loops through the serial ports registry. I need to keep the code as tight and small as possible. WOuld there be a better way to do it then the code below?

Func IsPortPresent($PortNum)

Local $Instance = 1, $Key, $Found = False, $Port

While 1

$Key = RegEnumVal("HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\SERIALCOMM", $Instance)

If @error = -1 Then

ExitLoop

EndIf

if $Key = "" and @error > 0 Then

WriteLog("Error " & @error & " preforming RegEnumVal")

ExitLoop

EndIf

$Port = RegRead("HKLM\HARDWARE\DEVICEMAP\SERIALCOMM",$Key )

If $Port = "" And @error <> 0 Then

WriteLog("Error " & @error & " preforming RegRead")

ExitLoop

EndIf

If $Port = ("COM" & $PortNum) Then

$Found = True

ExitLoop

EndIf

$Instance += 1

WEnd

if $Found = False Then

WriteLog("COM" & $PortNum & " is not present")

EndIf

Return $Found

EndFunc

[Inververs]

#include 'DeviceApi.au3'
Local $friendly_name, $aCom,$Count = 0
_DeviceAPI_GetClassDevices("{4D36E978-E325-11CE-BFC1-08002BE10318}")
While _DeviceAPI_EnumDeviceInfo($Count)
$friendly_name = _DeviceAPI_GetDeviceRegistryProperty($SPDRP_FRIENDLYNAME)
$Count += 1
If $friendly_name Then ConsoleWrite($friendly_name & @LF)
WEnd

[CountyIT]

Thanks Seeker. It kind of looks like they both search the registry in a loop. You think the deviceapi is going to be quicker and faster?

Dang. No luck. The deviceapi.au3 wasn't readily available. Someone posted a link toward the end of the thread but what I tried to run the above script it couldn't find any of the functions...

Edited January 22, 2013 by CountyIT