Question

How can I detect what port (Ne01:, Ne02:, Ne99: etc) the printer is on?

Computers (WinXP) here at BigCorp have Adobe Acrobat (version 7.0 Pro) installed which gives a virtual printer named “Adobe PDF”. If you print an Excel (2003) workbook to pdf while recording a macro, the printer’s full name is “Adobe PDF on Nexx:” where xx is a double digit…. and differs depending on what computer you try.

I have written a C# console app using the Excel.Interop (I strongly discourage anyone else from starting down this road to hell) that opens a series of spreadsheets. It runs a macro in each one, saves, prints is as a pdf, then moves the pdf to a reports folder on a shared drive.

The problem I face is that every install of Acrobat seems to pick a random port number for the PDF printer… and I can’t figure out how to get it.

So far I have tried using the Win32_Printer class like so

var searcher = new ManagementObjectSearcher( @"SELECT * FROM Win32_Printer" );
foreach ( ManagementObject printer in searcher.Get() )
{
   if ( Regex.IsMatch( printer["Name"].ToString(), @"(adobe|pdf)", RegexOptions.IgnoreCase ) )
   {
       //printer["Name"];    => "Adobe PDF"
       //printer["PortName"] => "my documents/*.pdf"
       foreach ( PropertyData pd in printer.Properties )
       {
           Console.WriteLine(string.Format("{0}, {1}", pd.Name, pd.Value));
       }
           break;
      }
}

I also poked around in the System.Drawing.Printing class. The PrinterSettings.InstalledPrinters will give you the name of the printer “Adobe PDF” but I can’t figure out how to get the port info.

If I pass just “Adobe PDF” to the excel interop PrintOut() method it sometimes works and sometimes fails with “Document failed to print”… I cannot figure out why.

If I pass a hardcoded “Adobe PDF on Ne0x:” with an appropriate x value it works every time.

If I try every possible variation, Excel helpfully prints to the default printer. I do not have the option of changing the default printer (security policy restriction)

Can anyone point me to code that correctly pulls the printer port?

Answer 1

Here’s what I ended up doing

using Microsoft.Win32;
...

        var devices = Registry.CurrentUser.OpenSubKey( @"Software\Microsoft\Windows NT\CurrentVersion\Devices" ); //Read-accessible even when using a locked-down account
        string printerName = "Adobe PDF";

        try
        {

            foreach ( string name in devices.GetValueNames() )
            {
                if ( Regex.IsMatch( name, printerName, RegexOptions.IgnoreCase ) )
                {
                    var value = (String)devices.GetValue( name );
                    var port = Regex.Match( value, @"(Ne\d+:)", RegexOptions.IgnoreCase ).Value;  
                    return printerName + " on " + port;
                }
            }
        }
        catch
        {
            throw;
        }