How to connect Rockwell PLC using C#?

I need to extract data in real time from a Rockwell brand PLC, guiding me through a tutorial I tried to make the PLC connection with SQL Server but I have to buy a library. That's why I want to make the connection using C# code in Visual Studio.The interface that I use for the Plc is similar to the one in the image. Any idea or suggestion will be fine received. PLC Interface