Open Communication With Serial Port throws ArgumentException

Question

I am trying to open communication with Com port 3, where is my printer connected. I would like to send commands from C# application directly to printer(emmulation commands) in order to check printer status. Printer is connected to my machine via Usb-To-Serial cable on COM3.

But when I try to open port I get ArgumentException - The port name does not begin with "COM". - or -The file type of the port is not supported.

When I go to device manager I can see printer driver and Usb driver set to same COM3, baud rate = 115200, Parity = none, DataBits = 8, StopBits = 1

Here is my code:

var printerPort = new SerialPort("COM3", 115200, Parity.None, 8, StopBits.One);
if(printerPort.IsOpen)
{
    printerPort.Close();
}
printerPort.ReadTimeout = 1400;
printerPort.WriteTimeout = 1000;
printerPort.Open();

I am not sure what I am doing wrong. Thanks in advance!