How to find available parallel ports and their I/O addresses using Delphi and WMI

Question

I see that WMI is very powerful and seems to be able to return most properties of a PC hardware. I'd like to display the available parallel ports on any PC and find their I/O addresses - I know that normally this is done using a Kernel driver but this is a legacy need - dont ask! Presently we look in Device Manager and then have to type in the address displayed there. I'd like to use WMI to find out this information. There are an excellent set of WMI classes at 1 but I cannot see how to iterate.

Thanks.

Answer 1

One must experiment to extract a complex information from WMI. I have tried to find the parallel port addresses on my PC and that is the report:

First of all I have queried Win32_ParallelPort class to find all parallel ports. (using the same code as PRUZ in his post before): 'Select * From Win32_ParallelPort'. The result is (I have only one parallel port in my system):

instance of Win32_ParallelPort
{
    Availability = 3;
    Caption = "LPT1";
    ConfigManagerErrorCode = 0;
    ConfigManagerUserConfig = FALSE;
    CreationClassName = "Win32_ParallelPort";
    Description = "LPT1";
    DeviceID = "LPT1";
    Name = "LPT1";
    OSAutoDiscovered = TRUE;
    PNPDeviceID = "ACPI\\PNP0401\\4&25C6B52A&0";
    PowerManagementSupported = FALSE;
    ProtocolSupported = 17;
    SystemCreationClassName = "Win32_ComputerSystem";
    SystemName = "JUPITER";
};

Second, I have queried Win32_PNPAllocatedResource ('Select * From Win32_PnPAllocatedResource'). I have got a lot of information here, but I have selected only the 3 entries by PNPDeviceID = "ACPI\PNP0401\4&25C6B52A&0".

instance of Win32_PNPAllocatedResource
{
    Antecedent = "\\\\JUPITER\\root\\cimv2:Win32_PortResource.StartingAddress=\"888\"";
    Dependent = "\\\\JUPITER\\root\\cimv2:Win32_PnPEntity.DeviceID=\"ACPI\\\\PNP0401\\\\4&25C6B52A&0\"";
};


instance of Win32_PNPAllocatedResource
{
    Antecedent = "\\\\JUPITER\\root\\cimv2:Win32_PortResource.StartingAddress=\"1912\"";
    Dependent = "\\\\JUPITER\\root\\cimv2:Win32_PnPEntity.DeviceID=\"ACPI\\\\PNP0401\\\\4&25C6B52A&0\"";
};


instance of Win32_PNPAllocatedResource
{
    Antecedent = "\\\\JUPITER\\root\\cimv2:Win32_DMAChannel.DMAChannel=3";
    Dependent = "\\\\JUPITER\\root\\cimv2:Win32_PnPEntity.DeviceID=\"ACPI\\\\PNP0401\\\\4&25C6B52A&0\"";
};

The third entry is of no interest. The first two entries gives us two (decimal) starting addresses (888 and 1912)

Finally I have queried Win32_PortResource ('Select * From Win32_PortResource') to find the ending addresses corresponding to the starting addresses 888 and 1912:

instance of Win32_PortResource
{
    Alias = FALSE;
    Caption = "0x00000378-0x0000037F";
    CreationClassName = "Win32_PortResource";
    CSCreationClassName = "Win32_ComputerSystem";
    CSName = "JUPITER";
    Description = "0x00000378-0x0000037F";
    EndingAddress = "895";
    Name = "0x00000378-0x0000037F";
    StartingAddress = "888";
    Status = "OK";
};


instance of Win32_PortResource
{
    Alias = FALSE;
    Caption = "0x00000778-0x0000077B";
    CreationClassName = "Win32_PortResource";
    CSCreationClassName = "Win32_ComputerSystem";
    CSName = "JUPITER";
    Description = "0x00000778-0x0000077B";
    EndingAddress = "1915";
    Name = "0x00000778-0x0000077B";
    StartingAddress = "1912";
    Status = "OK";
};

---

Updated

I have used the same code as RRUZ, in GUI application (see below). The only thing you need to compile it is the WbemScripting_TLB.pas unit. The unit is generated by type library import wizard, you can read about the process in Delphi 2009 in my blog

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Memo1: TMemo;
    Button4: TButton;
    Button5: TButton;
    Button6: TButton;
    procedure Button4Click(Sender: TObject);
    procedure Button5Click(Sender: TObject);
    procedure Button6Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

uses WbemScripting_TLB, ActiveX;


{$R *.dfm}


procedure TForm1.Button4Click(Sender: TObject);
var
  WMIServices  : ISWbemServices;
  WMILocator   : ISWbemLocator;
  Root         : ISWbemObjectSet;
  SWbemObject  : ISWbemObject;
  Item         : IEnumVariant;
  rgVar        : OleVariant;
  pCelFetched  : Cardinal;

begin
  Memo1.Lines.Clear;
  WMILocator := CoSWbemLocator.Create();
  WMIServices := WMILocator.ConnectServer('.', 'root\cimv2','', '', '', '', 0, nil);    //
  Root := WMIServices.ExecQuery('Select * From Win32_PnPAllocatedResource','WQL', 0, nil);
  Item :=  (Root._NewEnum) as IEnumVariant;
  while  (Item.Next(1, rgVar, pCelFetched) = S_OK) do
  begin
    SWbemObject := IUnknown(rgVar) as ISWBemObject;
    if (SWbemObject <> nil) then
    begin
      SWbemObject.Properties_;//Load the Properties to read
      Memo1.Lines.Add(SWbemObject.GetObjectText_(0));
    end;
  end;
end;

procedure TForm1.Button5Click(Sender: TObject);
var
  WMIServices  : ISWbemServices;
  WMILocator   : ISWbemLocator;
  Root         : ISWbemObjectSet;
  SWbemObject  : ISWbemObject;
  Item         : IEnumVariant;
  rgVar        : OleVariant;
  pCelFetched  : Cardinal;

begin
  Memo1.Lines.Clear;
  WMILocator := CoSWbemLocator.Create();
  WMIServices := WMILocator.ConnectServer('.', 'root\cimv2','', '', '', '', 0, nil);    //
  Root := WMIServices.ExecQuery('Select * From Win32_PortResource','WQL', 0, nil);
  Item :=  (Root._NewEnum) as IEnumVariant;
  while  (Item.Next(1, rgVar, pCelFetched) = S_OK) do
  begin
    SWbemObject := IUnknown(rgVar) as ISWBemObject;
    if (SWbemObject <> nil) then
    begin
      SWbemObject.Properties_;//Load the Properties to read
      Memo1.Lines.Add(SWbemObject.GetObjectText_(0));
    end;
   end;
end;

procedure TForm1.Button6Click(Sender: TObject);
var
  WMIServices  : ISWbemServices;
  WMILocator   : ISWbemLocator;
  Root         : ISWbemObjectSet;
  SWbemObject  : ISWbemObject;
  Item         : IEnumVariant;
  rgVar        : OleVariant;
  pCelFetched  : Cardinal;

begin
  Memo1.Lines.Clear;
  WMILocator := CoSWbemLocator.Create();
  WMIServices := WMILocator.ConnectServer('.', 'root\cimv2','', '', '', '', 0, nil);    //
  Root := WMIServices.ExecQuery('Select * From Win32_ParallelPort','WQL', 0, nil);
  Item :=  (Root._NewEnum) as IEnumVariant;
  while  (Item.Next(1, rgVar, pCelFetched) = S_OK) do
  begin
    SWbemObject := IUnknown(rgVar) as ISWBemObject;
    if (SWbemObject <> nil) then
    begin
      SWbemObject.Properties_;//Load the Properties to read
      Memo1.Lines.Add(SWbemObject.GetObjectText_(0));
    end;
   end;
end;

end.