There are several different nodes in DCS communication network, which are usually divided into two big categories, one of which is the node directly connected with the production process through I/O board, which is called the controller. According to different functions, the controllers can be divided into data acquisition controller and loop controller, which can be combined into one node. The other category of node is connected with the man-machine, which is called the man-machine interface. They collect data in the controller via the communication network. According to the functions, they are divided into operating stations, which not only read the data from the controller, but also send the operating personnel’s intention to the controller, so the data transmission is in two-way. Other nodes of man-machine interface are engineering workstation, historical trend and dynamic data server respectively. Usually only before the system is put into operation, can the Engineer workstation connects various algorithms stored in the controllers and fill in the parameters in the controllers according to the production requirements. It is the tool for configuration and it can be offline after the system is put into operation. The work of Engineer station differs with the algorithmic language programming, it is called configuration.