Mega Code Archive
Enumerating available comm ports with friendly names
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Title: Enumerating available comm ports with friendly names.
Question: Serial (and virtual serial) PNP Devices (PCMCIA, USB, Bluetooth) get assigned "arbitrary" comm port numbers.
To help users to select the correct comm port it would be helpfull to list them with device friendly names.
The supplied function helps this goal.
Answer:
(*
The function below returns a list of available COM-ports
(not open by this or an other process), with friendly names. The list is formatted as follows:
COM1: = Communications Port (COM1)
COM5: = NI Serial Port (Com5)
COM6: = NI Serial Port (Com6)
COM7: = USB Serial Port (COM7)
COM8: = Bluetooth Communications Port (COM8)
COM9: = Bluetooth Communications Port (COM9)
The function uses the setupapi (setup api) unit that is available from
"http://homepages.borland.com/jedi/cms/modules/apilib/visit.php?cid=4&lid=3".
I have verified the code and it worked for W2000, WXP, W98. It does not work for W95, and NT 4.0. I did not check WME but I guess it will work with WME too.
*)
function SetupEnumAvailableComPorts:TstringList;
// Enumerates all serial communications ports that are available and ready to
// be used.
// For the setupapi unit see
// http://homepages.borland.com/jedi/cms/modules/apilib/visit.php?cid=4&lid=3
var
RequiredSize: Cardinal;
Guid: TGUID;
DevInfoHandle: HDEVINFO;
DeviceInfoData: TSPDevInfoData;
MemberIndex: Cardinal;
PropertyRegDataType: DWord;
RegProperty: Cardinal;
RegTyp: Cardinal;
Key: Hkey;
Info: TRegKeyInfo;
S1,S2: string;
hc: THandle;
begin
Result:=Nil;
//If we cannot access the setupapi.dll then we return a nil pointer.
if not LoadsetupAPI then exit;
try
// get 'Ports' class guid from name
if SetupDiClassGuidsFromName('Ports',@Guid,RequiredSize,RequiredSize) then begin
//get object handle of 'Ports' class to interate all devices
DevInfoHandle:=SetupDiGetClassDevs(@Guid,Nil,0,DIGCF_PRESENT);
if Cardinal(DevInfoHandle)Invalid_Handle_Value then begin
try
MemberIndex:=0;
result:=TStringList.Create;
//iterate device list
repeat
FillChar(DeviceInfoData,SizeOf(DeviceInfoData),0);
DeviceInfoData.cbSize:=SizeOf(DeviceInfoData);
//get device info that corresponds to the next memberindex
if Not SetupDiEnumDeviceInfo(DevInfoHandle,MemberIndex,DeviceInfoData) then
break;
//query friendly device name LIKE 'BlueTooth Communication Port (COM8)' etc
RegProperty:=SPDRP_FriendlyName;{SPDRP_Driver, SPDRP_SERVICE, SPDRP_ENUMERATOR_NAME,SPDRP_PHYSICAL_DEVICE_OBJECT_NAME,SPDRP_FRIENDLYNAME,}
SetupDiGetDeviceRegistryProperty(DevInfoHandle,DeviceInfoData,
RegProperty,
@PropertyRegDataType,
NIL,0,@RequiredSize);
SetLength(S1,RequiredSize);
if SetupDiGetDeviceRegistryProperty(DevInfoHandle,DeviceInfoData,
RegProperty,
@PropertyRegDataType,
@S1[1],RequiredSize,@RequiredSize) then begin
KEY:=SetupDiOpenDevRegKey(DevInfoHandle,DeviceInfoData,DICS_FLAG_GLOBAL,0,DIREG_DEV,KEY_READ);
if keyINValid_Handle_Value then begin
FillChar(Info, SizeOf(Info), 0);
//query the real port name from the registry value 'PortName'
if RegQueryInfoKey(Key, nil, nil, nil, @Info.NumSubKeys,@Info.MaxSubKeyLen, nil, @Info.NumValues, @Info.MaxValueLen,
@Info.MaxDataLen, nil, @Info.FileTime) = ERROR_SUCCESS then begin
RequiredSize:= Info.MaxValueLen + 1;
SetLength(S2,RequiredSize);
if RegQueryValueEx(KEY,'PortName',Nil,@Regtyp,@s2[1],@RequiredSize)=Error_Success then begin
If (Pos('COM',S2)=1) then begin
//Test if the device can be used
hc:=CreateFile(pchar('\\.\'+S2+#0),
GENERIC_READ or GENERIC_WRITE,
0,
nil,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
0);
if hc INVALID_HANDLE_VALUE then begin
Result.Add(Strpas(PChar(S2))+': = '+StrPas(PChar(S1)));
CloseHandle(hc);
end;
end;
end;
end;
RegCloseKey(key);
end;
end;
Inc(MemberIndex);
until False;
//If we did not found any free com. port we return a NIL pointer.
if Result.Count=0 then begin
Result.Free;
Result:=NIL;
end
finally
SetupDiDestroyDeviceInfoList(DevInfoHandle);
end;
end;
end;
finally
UnloadSetupApi;
end;
end;
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