C# how to change a COM port to an specified one

Question

I need to change the port number of a USB serial adapter, i have the following rotine to finding it, now I need to change its portName / COM Number to COM11 for example.

I need exactly this, but by C# code:

My Computer -> Manage -> Device Manager -> Ports -> Communications Port -> Port Settings -> Advanced -> COM Port Number

        try
        {
            ManagementObjectSearcher searcher =
                new ManagementObjectSearcher("root\\WMI",
                "SELECT * FROM MSSerial_PortName");

            foreach (ManagementObject queryObj in searcher.Get())
            {
                //If the serial port's instance name contains USB 
                //it must be a USB to serial device
                if (queryObj["InstanceName"].ToString().Contains("USB"))
                {
                    Console.WriteLine("-----------------------------------");
                    Console.WriteLine("MSSerial_PortName instance");
                    Console.WriteLine("-----------------------------------");
                    Console.WriteLine("InstanceName: {0}", queryObj["InstanceName"]);
                    Console.WriteLine(queryObj["PortName"] + "is a USB to SERIAL adapter/converter");
                    string port = queryObj["PortName"].ToString();
                    SerialPort p = new SerialPort(port);
                    //p.PortName = "COM11";
                    return port ;
                }
            }

            throw new Exception(Messages.PINPAD_NOT_FOUND);
        }

if you are setting p.PortName where you have it commented out.. have you tried to uncomment it and return p.PortName.. ? also inside your method what's the return type can you show the full method..? — MethodMan
– MethodMan, Commented Jan 10, 2012 at 15:16
when doing something like this for example changing a printers Port there is a .Put(); method can you check to see if there is a p.Put(); before returning the port — MethodMan
– MethodMan, Commented Jan 10, 2012 at 15:24
Yep, p.PortName = "COM11" does not work, I've put it there to show what a want. SerialPort does not have such method as .Put(), I need some codo to update its settings — Carlos_rpg
– Carlos_rpg, Commented Jan 10, 2012 at 15:54
This is not an option, the driver picks the port number. Some drivers have a property page that lets you pick a number, not very common on USB drivers. You'll need to do this the other way around, provide config for your program so that the user can select the proper port number. — Hans Passant
– Hans Passant, Commented Jan 10, 2012 at 16:19
that's good to know @Hans.. sometimes WMI is awesome other times it can be a pain in the rear when doing something such as setting properties opposed to getting properties .. GRRRR.. — MethodMan
– MethodMan, Commented Jan 10, 2012 at 16:40

JPBlanc · Accepted Answer · 2012-01-12 10:07:49Z

1

I don't think com port renaming is available in wmi. On technical point of view the configuration you point change the symbolinc link attached to a driver. I think it's doable but you have to look a it in DDK (Perhaps in the WDM).

As far as I know, the proper solution for your program, is to be able to adapt itself to whatever name the hardware was assigned. You should store the correct port name in a configuration file or in the registry somewhere and allow the user to customize it.

answered Jan 12, 2012 at 10:07

JPBlanc

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1 Comment

Carlos_rpg Over a year ago

OK, it seems to be impossible. I had to talk to other company which my software work with to remove that requirement of Serial Port mapping. it will take a while for them to do it but that's it

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