Strong versatility, variable control program, easy to use
PLC has a complete variety of hardware devices, which can form a control system that can meet various requirements, and users do not need to design and make hardware devices by themselves. After the hardware is determined, the user does not need to change the hardware of the PLC when the production process is changed or the production equipment is updated, but only needs to reprogram the program to meet the requirements. Therefore, in addition to being used in stand-alone control, PLC is also widely used in factory automation.
Strong function and wide adaptability
Modern PLC not only has functions such as logic operation, timing, counting, sequence control, but also digital and analog input and output, power drive, communication, man-machine dialogue, self-test, record display and other functions. It can control both a production machine, a production line, and a production process.
Simple programming and easy to master
At present, most PLCs still use the “ladder diagram programming method” in the form of relay control. It not only inherits the clear and intuitive traditional control circuit, but also takes into account the reading habits and programming level of electrical technicians in most factories and enterprises, so it is very easy to accept and master. The symbols and expressions of the programming elements of the ladder language are quite close to the schematic diagram of the relay control circuit. By reading the PLC user manual or short-term training, electrical technicians and technicians can quickly learn to create control programs in ladder diagrams. It also provides programming languages such as function diagrams and statement lists.
When the PLC executes the ladder diagram program, it uses the interpreter program to translate it into assembly language and then execute it (the interpreter program is added inside the PLC). Compared with directly executing the user program written in assembly language, the time to execute the ladder diagram program is longer, but for most electromechanical control equipment, it is trivial and can fully meet the control requirements.
Reduce the workload of control system design and construction
Since PLC uses software to replace a large number of intermediate relays, time relays, counters and other devices in the relay control system, the design, installation and wiring workload of the control cabinet is greatly reduced. At the same time, the user program of PLC can be simulated and debugged in the laboratory, which reduces the workload of debugging on site. Moreover, due to the low failure rate and strong monitoring function of PLC, modularization, etc., maintenance is also extremely convenient.
Small size, light weight, low power consumption and easy maintenance
PLC is a product that applies microelectronics technology to industrial equipment, and its structure is compact, sturdy, small in size, light in weight and low in power consumption. And because of the strong anti-interference ability of PLC, it is easy to be installed into the equipment, and it is an ideal control equipment for realizing mechatronics. Take Mitsubishi’s F1-40M PLC as an example: its external size is only 305×110×110mm, its weight is 2.3kg, and its power consumption is less than 25VA; it also has a good ability to resist vibration and adapt to changes in ambient temperature and humidity. Now Mitsubishi has FX series PLC. Compared with its ultra-small F1 series, the area is 47% and the volume is 36%. The system configuration is both fixed and flexible, and the input and output can reach 24 to 128 points.
