Fix c# wpf asp.net code. Call 1 instance class method from other class several instan

Job should starts immediately after hiring.

Fix some c# wpf asp.net code issue using remote software control.

I'm newbie in C# and dont know how to deal with calls between diferent classes.. Maybe one just dependency injection works, maybe not (still, dont know how to do that)

Project constains:
- SerialPort class - a class that manages serial port communications
- Openport
- sendcommand
- datareceived methods


- Machine class - a class with several properties and methods. One in particular should use serial port communication
refreshvalues method()
- call commands and receives data



- Service class
creates several instances of Machine class
- ListMachine.Add(....)
- calls Machine.foreach .... Refreshvalues every 1 second

Since the a serial port can be open (and maintain it open) one time in application, serialport class should be one single instance, how can I call it from Machine classes...