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I’m trying to read and write to a usb modem that is using the com port 3 with this code.
SerialPort sp = new SerialPort();
sp.PortName = "COM3";
//sp.DataReceived += new SerialDataReceivedEventHandler(sp_DataReceived);
sp.Open();
sp.Write("AT<CR>");
byte[] bytes = new byte[sp.BytesToRead];
sp.Read(bytes, 0, sp.BytesToRead);
textBox1.Text = Encoding.UTF8.GetString(bytes);
But I get this error :
Access to the port ‘COM3’ is denied.
Someone have an idea …
Thanks
You can only open the port once. Maybe you’re accidentally opening it more than once within your code or another program is using it?