High reliability

Hardware design: PLC adopts highly integrated electronic components and has strong anti-interference ability in hardware design. For example, its internal power module usually has multiple filtering and voltage stabilizing measures, which can work stably in the common voltage fluctuation environment of industrial sites and reduce faults caused by power supply problems.

Input and output (I/O) interfaces use photoelectric isolation technology, which can effectively prevent external electromagnetic interference, surge voltage, etc. from affecting the internal circuit of PLC and ensure the accuracy and stability of data transmission.

Software design: The software of PLC has self-diagnosis function and can monitor the running state of the system in real time. For example, it can detect the running status of the CPU, memory usage, and the working status of each I/O module. Once an abnormality is found, PLC can issue an alarm in time and take corresponding protection measures, such as automatically switching to a standby system or stopping running a specific program segment to avoid further expansion of faults.

Strong Flexibility

Flexible programming: PLC adopts easy-to-understand and master programming languages, such as ladder diagram, instruction list, function block diagram, etc. These programming languages are similar to electrical control circuit diagrams and are relatively intuitive for electrical engineers and technicians. Taking ladder diagram as an example, it can easily realize functions such as logic control, timing, and counting. Technicians can quickly write and modify programs according to actual control needs.

The program of PLC is stored in non-volatile memory, which means that the program will not be lost after the device is powered off. When the production process needs to be changed, technicians can easily modify and debug the program without rewiring or replacing hardware equipment, greatly saving time and cost.

Convenient expansion: PLC has rich I/O expansion modules. Whether it is necessary to increase digital input and output points or analog input and output channels, it can be achieved by adding corresponding expansion modules. For example, in an automated production line, as the production scale expands, more sensors and actuators are needed to control the production process. At this time, only by adding I/O expansion modules to the PLC system can new control requirements be easily met.

Network communication function enables PLC to be integrated with other devices. PLC can exchange data and work collaboratively with upper computers (such as industrial computers), other PLCs, frequency converters, intelligent instruments and other devices through communication methods such as Ethernet and fieldbus to build a complex automated control system.

High Control Precision

Precise timing control: The timer inside PLC has very high timing precision, usually reaching millisecond level or even higher. In industrial production, for some operations that require precise timing, such as feeding time control in chemical reaction processes and sealing time control in packaging machinery, PLC can accurately realize timing operations to ensure the stability of the production process and product quality.

Precise analog processing: PLC has strong analog processing ability. It can collect continuously changing physical quantities such as temperature, pressure, and flow through the built-in analog input module and convert them into digital quantities for processing. In the processing process, PLC can use advanced control algorithms, such as PID (proportional-integral-derivative) control algorithm, to precisely adjust and control analog quantities. For example, in the temperature control of industrial boilers, PLC can precisely control the fuel supply according to the real-time temperature data collected by the temperature sensor through the PID algorithm, so that the boiler temperature is stable near the set value, improving energy utilization efficiency and production safety.

Simple Operation

Simple programming operation: As mentioned earlier, the programming language of PLC is easy to learn. For technicians without a deep foundation in computer programming, they can master the programming method of PLC through short-term training. Taking ladder diagram programming as an example, its programming interface is intuitive, and the operation steps are similar to drawing electrical control schematic diagrams. Technicians can quickly start programming.

Simple operation in running: PLC usually has a simple and clear human-machine interface (HMI), which can be operated and display status through touch screens, buttons, indicator lights, etc. During the operation of the equipment, operators can conveniently start and stop the equipment, set operating parameters, view the operating status and fault information of the equipment through the HMI. For example, in an automated packaging production line, operators can easily set packaging specifications, production speed and other parameters through the operation interface on the touch screen, monitor the operation of the production line, and deal with equipment failures in time.

High Cost Performance

Reasonable initial investment cost: Compared with the traditional relay-contactor control system, although the hardware cost of PLC itself is relatively high, considering the convenience of PLC system in design, installation, debugging and maintenance, the development cycle and labor cost of the system can be greatly reduced. For example, in a large electrical control system, if relay-contactor control is used, a large number of relays, contactors, timers, counters and other electrical components are needed, and the wiring is complex. Moreover, wiring errors and other problems are easy to occur during the debugging process. While using PLC system, only one PLC host and a small number of I/O modules are needed, and complex control functions can be realized through programming, reducing the initial investment cost of the system.

Low long-term operating cost: PLC has high reliability and stability, low failure rate and relatively low maintenance cost in the long-term operation. Moreover, the service life of PLC is relatively long, generally reaching more than 10 years. In addition, due to the flexibility of PLC, when the production process changes, only the program needs to be modified without replacing a large number of hardware equipment, further reducing the long-term operating cost. For example, in an automobile manufacturing factory, as the vehicle models are updated, the control requirements of the production line will change. Using PLC can conveniently transform and upgrade the production line without generating high equipment replacement costs.

Industrial Automation Field

Manufacturing industry

Assembly line: PLC can be used to control equipment such as robotic arms, conveyor belts, and tightening tools on the assembly line. For example, in an automobile assembly plant, PLC coordinates the operations of various workstations to ensure that engine, body parts, interior trim, etc. are assembled accurately and improve production efficiency and product quality.

Machining tools: In numerical control machines, milling machines, drilling machines and other processing equipment, PLC is responsible for controlling operations such as tool feed, spindle speed, and table movement. Through precise programming, PLC can achieve the processing of complex parts and conduct real-time monitoring and adjustment during the processing.

Metallurgical industry

Blast furnace ironmaking: PLC is used to control operations such as charging, blast, temperature regulation, etc. of the blast furnace. It can automatically adjust the addition amount of various materials and blast volume according to parameters such as temperature, pressure, and composition in the furnace to ensure stable and efficient ironmaking process.

Steel rolling production line: During the steel rolling process, PLC controls the reduction of rolling rolls, rolling speed, and steel transportation. For example, in a hot-rolled strip production line, PLC can realize the automatic control of the entire production line to ensure that indicators such as strip thickness, width, and flatness meet the requirements.

Power System

Substation automation: PLC is used for switch control, action logic of protection devices, data acquisition and monitoring in substations. It can monitor the operating status of equipment such as transformers, circuit breakers, and disconnectors in real time. When a fault occurs, PLC can quickly make judgments and control the action of protection devices, such as tripping the circuit breaker of the faulty line to ensure the safe and stable operation of the power system.

Power distribution and management: In smart grids, PLC can be used to realize access control and power distribution management of distributed energy sources (such as solar power plants and wind farms). For example, PLC can reasonably distribute power according to the load situation of the grid and the output power of distributed energy sources to optimize the operation of the grid and improve energy utilization efficiency.

Architecture And Infrastructure

Elevator control: PLC is the core of modern elevator control systems. It controls operations such as elevator ascent and descent, door opening and closing, and floor stops. Through programming, PLC can realize multiple operation modes of elevators, such as single elevator automatic operation and group elevator intelligent scheduling, improving elevator operation efficiency and ride comfort while ensuring elevator operation safety.

Heating, ventilation, and air conditioning (HVAC) system: In large building HVAC systems, PLC is used to control the start and stop of air conditioning units, temperature regulation, and air volume distribution. For example, in office buildings and shopping malls, PLC can automatically adjust the operating parameters of the air conditioning system according to factors such as indoor and outdoor temperatures and personnel density to achieve energy-saving operation.

Transportation

Traffic signal control: PLC is widely used in the control of urban traffic lights. It can automatically adjust the duration and switching sequence of traffic lights according to real-time data such as traffic flow and pedestrian flow to optimize traffic flow and reduce traffic congestion. For example, during peak hours, PLC can extend the green light time of main roads to improve road capacity.

Railway signal and interlocking system: In railway transportation, PLC is used to control the interlocking relationship of railway signal lights, switches, and routes. It ensures the safety of trains during operation and prevents train collisions and rear-end accidents. For example, in stations and sections, PLC accurately controls signal display and switch conversion according to the running position of trains and dispatching commands.

Water Treatment And Environmental Protection

Sewage treatment plant: PLC is used to control various links in the sewage treatment process, such as sewage lifting, aeration, sedimentation, filtration, and disinfection. It can automatically adjust the operating parameters of treatment equipment according to parameters such as sewage flow and water quality to ensure that sewage is discharged up to standard. For example, in an aeration tank, PLC can control the speed of the aeration fan according to the dissolved oxygen concentration to improve sewage treatment efficiency.

Water supply system: In urban water supply systems, PLC is used to control the start and stop of water pumps, pipe network pressure regulation, and water quality monitoring. For example, in secondary water supply pumping stations, PLC can reasonably control the operation of water pumps according to user's water demand to ensure stable water supply pressure.

Food And Beverage Industry

Food processing production line: In the food processing process, PLC is used to control various processing equipment such as cutting, mixing, baking, and packaging. For example, on a biscuit production line, PLC controls the mixing time of dough, baking temperature and time, and the packaging quantity of biscuits to ensure food production quality and hygiene safety.

Beverage filling production line: In beverage production, PLC controls operations such as beverage filling volume, cap tightening, and label pasting. For example, on a beer filling line, PLC can accurately control the filling volume of each bottle of beer to ensure product consistency and also monitor the hygiene situation during the filling process.