The automobile assembly line is composed of body storage section, chassis assembly section, door sub assembly and conveying section, final assembly section, power component assembly section, assembly section, front beam sub assembly section, rear axle sub assembly section, instrument panel assembly section, engine assembly section, etc.

Mitsubishi PLC and field bus CC link are the core control equipment of the whole system. Proximity or photoelectric switch is used to monitor the position of the executive structure. Mitsubishi FR-E500 series frequency converter is used to control the speed regulation part. All kinds of control signals and executive elements on site are controlled by PLC through CC link.

CC link network composed of CC link module is an open field bus. It can process control and information data at the same time. The industrial equipment is connected to the network of equipment layer through simple bus. It can also be easily connected to other networks.

All sections of the general assembly line are divided into automatic operation and manual operation. In automatic mode, the whole line is controlled by PLC program; in manual mode, operators operate on site. The whole line shall be equipped with emergency stop and alarm devices at necessary positions.

The electric control system of the general assembly line adopts the mode of "centralized supervision and decentralized control". The whole system is divided into three layers, namely information layer, control layer and equipment layer.

The information layer is composed of operator station and engineer station installed in the central control room. The main function of the operation station is to send control instructions to the field equipment and actuator, and collect and monitor the production data, operation status and fault information on site; the main role of the engineer station is to formulate production plan and manage production information. The Ethernet module installed on the PLC of MELSECNET / 10 network master station is used to realize the data exchange between them and each PLC in the equipment control layer. When necessary, the engineer station can be connected with the computer network of the management, so that the manager can look up the information needed in the office.

The control layer adopts Mitsubishi MELSECNET / 10 network to connect 8 sets of q2asplc on each section of the general assembly line (except the front axle and rear axle sub assembly section) to realize data sharing. It has the characteristics of high transmission speed (10Mbps), simple programming (without special network instructions), high reliability, convenient maintenance and large information capacity. A Mitsubishi a975got man-machine interface is used in the body storage section to realize the high-speed response to the field information of the section.

Four sets of CC link are used in the equipment layer, which are respectively hung on the PLC of body storage section, chassis assembly section, door sub assembly storage section and interior decoration section. CC link fieldbus has the characteristics of high transmission speed (up to 10Mbps), long transmission distance (1200m), simple setting, high reliability, convenient maintenance and low cost. It connects the sensors, pumps, valves, ID readers, frequency converters and remote I / O devices through twisted pair wires to realize the centralized management of decentralized control. In this way, the parameters, alarm information and other data of frequency converter can not only be read and written by PLC, but also monitored and adjusted by upper computer and got through PLC. The ID reader is easy to track the car body, reduce the information flow, make the production line structure highly flexible, and effectively improve the degree of automation, and save human resources.

The trial operation of the system is good, and any equipment failure in the system will not affect the operation of other operations, processes and equipment. Even if any equipment in the system fails or even drops off the line, only the equipment where the fault occurs cannot operate automatically, and all other equipment will work continuously. When the fault is eliminated, the equipment can automatically resume operation without re energizing the whole production line.

At the same time, the production data is collected and monitored in real time, and necessary repair operations can be carried out according to the production data. These production data (including product quality information) are stored in the upper computer and managed by the upper computer.