How to determine if a machine physically has a serial port?

Question

I could try to open it, but if it is use by another program I will get an error and I need to be able to distinguish that case from the case where the machine physically has no serial port.

Any idea?

By peeping into the back of the machine :) – Shrinath Apr 07 '11 at 03:08 — Shrinath, Apr 07 '11 at 03:08
Back in good old days I could have used PEEK() +1 – Mawg says reinstate Monica Apr 07 '11 at 03:48 — Mawg says reinstate Monica, Apr 07 '11 at 03:48

score 8 · Answer 1 · answered Apr 07 '11 at 04:40

Just for complement the Serg answer, the Win32_SerialPort class used in this article reports the physical com ports, if you wanna enumerate all the serial ports including the USB-Serial/COM ports, you must use the MSSerial_PortName class located in the root\wmi namespace.

uses
  SysUtils,
  ActiveX,
  ComObj,
  Variants;

// Serial Port Name

procedure  GetMSSerial_PortNameInfo;
const
  wbemFlagForwardOnly = $00000020;
var
  FSWbemLocator : OLEVariant;
  FWMIService   : OLEVariant;
  FWbemObjectSet: OLEVariant;
  FWbemObject   : OLEVariant;
  oEnum         : IEnumvariant;
  iValue        : LongWord;
begin;
  FSWbemLocator := CreateOleObject('WbemScripting.SWbemLocator');
  FWMIService   := FSWbemLocator.ConnectServer('localhost', 'root\WMI', '', '');
  FWbemObjectSet:= FWMIService.ExecQuery('SELECT * FROM MSSerial_PortName','WQL',wbemFlagForwardOnly);
  oEnum         := IUnknown(FWbemObjectSet._NewEnum) as IEnumVariant;
  while oEnum.Next(1, FWbemObject, iValue) = 0 do
  begin
    Writeln(Format('Active          %s',[FWbemObject.Active]));// Boolean
    Writeln(Format('InstanceName    %s',[FWbemObject.InstanceName]));// String
    Writeln(Format('PortName        %s',[FWbemObject.PortName]));// String

    Writeln('');
    FWbemObject:=Unassigned;
  end;
end;


begin
 try
    CoInitialize(nil);
    try
      GetMSSerial_PortNameInfo;
      Readln;
    finally
    CoUninitialize;
    end;
 except
    on E:Exception do
    begin
        Writeln(E.Classname, ':', E.Message);
        Readln;
    end;
  end;
end.

for additional info about the serial ports try the classes located in the same namespace

MSSerial_CommInfo
MSSerial_CommProperties
MSSerial_HardwareConfiguration
MSSerial_PerformanceInformation

score 3 · Accepted Answer · answered Apr 07 '11 at 03:20

3

You can use WMI. Have a look at my old post

answered Apr 07 '11 at 03:20

kludg

27,213
5
67
118

+1 That looks great. I'll go to lunch, come back & code it then award the answer if it works (and I am sure that it will). Thanks – Mawg says reinstate Monica Apr 07 '11 at 03:49
1

the Win32_SerialPort doesn't contain any USB serial ports (as RRUZ hinted) – BennyBechDk Apr 07 '11 at 12:40

score 2 · Answer 3 · edited May 23 '17 at 12:26

2

You could also read from registry:
Enumerating a List of systems Com Ports in Delphi

edited May 23 '17 at 12:26

Community

1
1

answered Apr 07 '11 at 12:32

BennyBechDk

934
7
13

How to determine if a machine physically has a serial port?

3 Answers3

Linked