There are many forms of controller networking, which can be divided into two categories: there is no router between the controller and the computer, and there is router between the controller and the computer.

There is a router between the controller and the computer, that is, the IP addresses of the controller and the computer are not in the same network segment. This connection method can be divided into computer and router in the same network segment, and the controller is at the lower level of the router. Banks, stations and hospitals often use this connection method, which is more suitable for centralized control. The other is that the controller and router are in the same network segment, and the control computer is at the lower level of the router. This connection method is generally not used much.