PLC Advantages and Disadvantages

High reliability and strong anti-interference ability.

Industrial production generally has high requirements on the reliability of control equipment, and must have a strong anti-interference ability.

PLC can work reliably in harsh environments, with an average trouble-free time of more than tens of thousands of hours, which has been recognized as one of the most reliable industrial control equipment.

The PLC itself has a strong self-diagnosis function to ensure that the hardware core equipment (CPU, memory, I / O bus, etc.) executes the user program under normal circumstances.

If a fault occurs, an error signal is immediately given to stop the execution of the user program and cut off All output signals are waiting for repair.

The main modules of PLC are large-scale and ultra-large-scale integrated circuits, and the I / O system is designed with perfect channel protection and signal conditioning circuits.

The structure has precise considerations for heat resistance, moisture resistance, dust prevention, earthquake resistance, etc. Anti-interference measures such as isolation, shielding, filtering, and grounding are used in hardware, and digital filtering and other measures are used in software.

Compared with the relay system and general-purpose computer, PLC can better adapt to the requirements of industrial field environment.

Complete hardware, easy to use and strong adaptability

PLC is controlled by executing programs. When the control requirements change, as long as the program can be modified, the time required for the process update is minimized.

PLC products have been standardized, serialized, and modularized, and there are many types of PLC and supporting products.

Users can flexibly and conveniently configure the system and combine them into various control systems with different scales and different functions.

In the PLC control system, only the corresponding input / output signal lines need to be connected to the terminals of the PLC, no large and complicated hard wiring is required, and the PLC has a strong load capacity, which can directly drive the general Solenoid valve and AC contactor.

Intuitive programming, easy to learn and easy to learn

PLC provides a variety of programming languages, of which the ladder diagram is most commonly used. PLC is a user-oriented device.

The designers of PLC fully consider the skills and habits of on-site engineering and technical personnel. Therefore, the preparation of PLC programs adopts the simple instruction form of ladder diagram.

The ladder diagram is similar to the relay schematic diagram. This programming language is intuitive, easy to learn and understand, and does not require special computer knowledge and language.

Field engineering technicians can learn to use it in a short time. After purchasing PLC, users only need to do a small amount of wiring and carry out simple user programming according to the instructions in the manual, and then they can flexibly and conveniently apply PLC to production practice.

The system design, installation and commissioning work load is small, easy maintenance

PLC has replaced a large number of intermediate relays, time relays, counters and other devices in the relay control system with software, which greatly reduces the workload of design, installation and wiring of the control cabinet.

At the same time, most of the PLC user programs can be simulated and debugged in the laboratory. After the simulation and debugging, the PLC control system is installed on the production site for online debugging, which is safe, fast and convenient.

The failure rate of PLC is very low, and it has perfect self-diagnosis and display functions. When a fault occurs, you can quickly find the cause of the fault according to the PLC status indicator display or the information provided by the programmer to eliminate the fault.

Small size and low energy consumption

Because PLC uses semiconductor integrated circuits, its small size, light weight, compact structure, low power consumption, and easy installation are ideal controllers for mechatronics.

For complex control systems, the use of PLC can generally reduce the volume of the switchgear to 1/10 ~ 1/2.

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