The hardware structure of the direct digital control system is templating and modular. The installation method can be divided into the following types:
1. Box type. It integrates the main control unit, the input and output unit and the operation display unit. The front of the box is an LCD display and a membrane keyboard. The box structure is small in size and light in weight, and can be directly installed on production equipment, which is convenient for on-site operation monitoring and is suitable for small data acquisition and control systems.
2. Desktop. It concentrates the main control unit and the input and output unit in one chassis, and then places the chassis and the display, keyboard, mouse, and printer on the console or terminal table. The benchtop structure is bulky and has many components for medium-sized data acquisition and control systems.
3. Cabinet type. It concentrates the main control unit in the main chassis, the input and output units are concentrated in the I/O chassis, or the two units are concentrated in one chassis. These chassis are suitable for disc or cabinet installation, and then the display The keyboard, mouse, and printer are placed on the console or terminal desk. The cabinet structure is large in size and has many components, and is suitable for large data acquisition systems or control systems of relatively large scale.