Serial port enumeration in Delphi using SetupDiGetClassDevs - delphi

Question

I'm trying to enumerate "friendly names" for COM ports. The ports may dynamically change as USB-serial devices are connected and disconnected at runtime.
Based on the possible methods described in this question, I am attempting to use the SetupDiGetClassDevs method.
I found this example code, but it is written for an older version of the setupapi unit (the original link to homepages.borland.com doesn't work of course).
I tried using the setupapi unit from the current JVCL(JVCL340CompleteJCL221-Build3845), but it doesn't seem to be compatible with Delphi 7. I get compiler errors:
if SetupDiGetDeviceRegistryProperty(DevInfoHandle,DeviceInfoData,
RegProperty,
#PropertyRegDataType,
#S1[1],RequiredSize,#RequiredSize) then begin
In the call to function SetupDiGetDeviceRegistryProperty,
I get the error "Types of actual and formal parameters must be identical" on the parameters #PropertyRegDataType, and #RequiredSize.
The Delphi3000 site says the code was written in 2004 and is intended for Delphi 7, so I'm not sure why it doesn't work with Delphi 7 now, unless setupapi has changed. Is anyone familiar with the changes to setupapi that could cause these problems?
I'm testing with a simple console program. The uses statement is " windows,
sysutils,
classes,
setupAPI,
Registry;"
The main program is:
begin
ComPortStringList := SetupEnumAvailableComPorts;
for Index := 0 to ComPortStringList.Count - 1 do
writeln(ComPortStringList[Index]);
end;
end.

Answer 1

The following procedure is working correctly for me (in Windows 8.1). It is important to use the parameter KEY_READ in the TRegistry.Constructor.
procedure EnumComPorts(const Ports: TStringList);
var
nInd: Integer;
begin { EnumComPorts }
with TRegistry.Create(KEY_READ) do
try
RootKey := HKEY_LOCAL_MACHINE;
if OpenKey('hardware\devicemap\serialcomm', False) then
try
Ports.BeginUpdate();
try
GetValueNames(Ports);
for nInd := Ports.Count - 1 downto 0 do
Ports.Strings[nInd] := ReadString(Ports.Strings[nInd]);
Ports.Sort()
finally
Ports.EndUpdate()
end { try-finally }
finally
CloseKey()
end { try-finally }
else
Ports.Clear()
finally
Free()
end { try-finally }
end { EnumComPorts };

Answer 2

I was able to get some more specific suggestions by asking the question a different way with different tags.
It turns out there were errors in the delphi3000.com example code, and possibly errors in the JVCL code. After fixing the example code errors, I got it to work. I have not addressed the potential JVCL errors.
Here is the working code (as a simple console app) for enumerating the names of com ports:
{$APPTYPE CONSOLE}
program EnumComPortsTest;
uses
windows,
sysutils,
classes,
setupAPI,
Registry;
{$R *.RES}
var
ComPortStringList : TStringList;
(*
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)
This code originally posted at http://www.delphi3000.com/articles/article_4001.asp?SK=
errors have been fixed so it will work with Delphi 7 and SetupAPI from JVCL
*)
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;
GUIDSize: DWORD;
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
GUIDSize := 1; // missing from original code - need to tell function that the Guid structure contains a single GUID
if SetupDiClassGuidsFromName('Ports',#Guid,GUIDSize,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 key<>INValid_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;
var
index : integer;
begin
ComPortStringList := SetupEnumAvailableComPorts;
if (ComPortStringList <> nil) and (ComPortStringList.Count > 0) then
for Index := 0 to ComPortStringList.Count - 1 do
writeln(ComPortStringList[Index]);
end.

Answer 3

Looks like some arguments of type PDWord were replaced by var DWord in SetupApi.pas. All you need is to remove '#' from these arguments in your code like that:
if SetupDiGetDeviceRegistryProperty(DevInfoHandle,DeviceInfoData,
RegProperty,
PropertyRegDataType,
#S1[1],RequiredSize,RequiredSize) then begin

Answer 4

Do you have "typed # operator" turned on? Project options, Compiler tab under "Syntax options". A lot of third party code breaks if that option is enabled.

Answer 5

For easier operation you might consider simply using the registry where those names are listed eg:
ErrCode := RegOpenKeyEx(
HKEY_LOCAL_MACHINE,
'HARDWARE\DEVICEMAP\SERIALCOMM',
0,
KEY_READ,
KeyHandle);
(I've ommited the hand-waving stuff).
You might also consider using WMI - see this example from Magenta Systems - you can get a pretty much everything hardware-related now.

Answer 6

I adapted below code from RRUZ answer for Serial Port class. Works fine under Win10 20H2.
{$APPTYPE CONSOLE}
uses
SysUtils,
ActiveX,
ComObj,
Variants;
procedure GetWin32_SerialPortInfo;
const
WbemUser ='';
WbemPassword ='';
WbemComputer ='localhost';
wbemFlagForwardOnly = $00000020;
var
FSWbemLocator : OLEVariant;
FWMIService : OLEVariant;
FWbemObjectSet: OLEVariant;
FWbemObject : OLEVariant;
oEnum : IEnumvariant;
iValue : LongWord;
begin;
FSWbemLocator := CreateOleObject('WbemScripting.SWbemLocator');
FWMIService := FSWbemLocator.ConnectServer(WbemComputer, 'root\CIMV2', WbemUser, WbemPassword);
FWbemObjectSet:= FWMIService.ExecQuery('SELECT * FROM Win32_SerialPort','WQL',wbemFlagForwardOnly);
oEnum := IUnknown(FWbemObjectSet._NewEnum) as IEnumVariant;
while oEnum.Next(1, FWbemObject, iValue) = 0 do
begin
// for other fields: https://learn.microsoft.com/en-us/windows/win32/cimwin32prov/win32-serialport
Writeln(Format('DeviceID %s',[String(FWbemObject.DeviceID)]));// String
Writeln(Format('Name %s',[String(FWbemObject.Name)]));// String
Writeln(Format('Description %s',[String(FWbemObject.Description)]));// String
FWbemObject:=Unassigned;
end;
end;
begin
try
CoInitialize(nil);
try
GetWin32_SerialPortInfo;
finally
CoUninitialize;
end;
except
on E:EOleException do
Writeln(Format('EOleException %s %x', [E.Message,E.ErrorCode]));
on E:Exception do
Writeln(E.Classname, ':', E.Message);
end;
Writeln('Press Enter to exit');
Readln;
end.
Output:
DeviceID COM7
Name Silicon Labs CP210x USB to UART Bridge (COM7)
Description Silicon Labs CP210x USB to UART Bridge
Press Enter to exit