
The structure block diagram of arm based distributed processing unit is shown in Figure 2, which is very similar to the structure of general distributed processing unit. Here, the processing unit is mainly divided into six parts: arm controller, upper network module, power management module, memory module, lower network module and clock module. Arm controller and memory module constitute the most basic embedded system. The data processing and control strategy of the whole DCS control system are processed here. The upper network module mainly refers to the main / redundant network communicating with the management and a network realizing the data exchange of the main / redundant distributed processing unit. The main function of this part is to complete the real-time detection of the DCS control system by the management and realize the data redundancy of the main / redundant distributed processing unit. The bottom network module is composed of two 485 networks divided into primary and secondary. This module mainly realizes the data communication between the i/o cards of the arm controller. The memory module can be divided into two parts, one is used to manage and store the operating system, and the other is used to manage and store real-time data. The power module and the clock module realize the management of power supply and clock respectively.