Explore the programmable logic control (PLC)

PLCs, definitions, advantages, and applications

Nowadays, the automation level especially the industrial one is transferred to a higher level where new strategies and control algorithms have been developed and play a crucial role in the industrial automation systems for monitoring and controlling the industrial process to achieve targets and maximize process performance.

Programmable Logic Control PLC

We discussed the automation system in previous articles and explained control's role. We also stated the importance of the PID controller in industrial optimization. In this article, we will review an essential and amazing system used in industrial control called Programmable Logic Control (PLC). Let us start that journey.

What is the definition of PLC?

Programmable Logic Control (PLC) is a specialized form of technology in industrial automation that uses programmable controllers to monitor, control, and automate various industrial processes and manufacturing machinery.

PLCs are created and designed to monitor the collected signals from field sensors and other measurement devices, process this information based on a preprogrammed logic sequence, and control output signals to the process drives like valves, actuators, and motors to execute certain tasks.

PLCs replaced traditional control systems such as relay-based and offer huge advantages over that type of control. It is reliable, scalable, flexible, and easy for operation, troubleshooting, and programming. It can be integrated with cloud, IoT connectivity, and artificial intelligence, to maximize the efficiency in industrial processes.

What are the 8 advantages of PLC?

Programmable Logic Controllers (PLCs) are important in industrial automation and control systems because of their advantages and functionalities. The importance of PLCs in industrial automation can be concluded as follows:

1. Productivity and Efficiency increasing. By automating repetitive tasks and optimizing processes, PLCs increase the efficiency and productivity in industrial operations. It can execute huge and complicated sequences of operations quickly and accurately to faster production cycles and reduce downtime.
2. Improved Quality Control. PLCs enable more precise control over manufacturing processes, ensuring high accuracy in product quality. By monitoring and adjusting process parameters, PLCs maintain high-quality standards.
3. Flexibility. PLCs are flexible in programming and allow easy modifications to adjust the changes in production processes. It adapts to different tasks without the need for extensive rewiring or hardware changes.
4. Reliability. Programmable logic control offers a reliable control system for automating industrial processes automation system where it can monitor and control various parameters accurately such as position, speed, temperature, and pressure to ensure the good operation of machinery and equipment.
5. Cost optimization. Compared to traditional control systems, PLCs provide a cost optimization approach in automation solutions. PLCs are maintenance-free and need less wiring. It doesn’t need any programming which is considered a cost-saving approach.
6. Easy Monitoring and faults troubleshooting. Programmable logic control offers remote monitoring and easy faults troubleshooting that enable operators to follow up on the process performance and make the needed adjustments remotely. This feature enables the monitoring and control of industrial processes from anywhere.
7. Integration with Other Systems: PLCs enable easy connection with other control systems, sensors, actuators, and communication networks to build a comprehensive automation solution. They enable also data exchange and communication between different types of control systems.
8. Increase Safety: PLCs play a significant role in ensuring the safety of both human and industrial processes by implementing safety protocols logic inside the program that matches each process based on its type and application and may enable the complete shutdown in emergency cases.

What are the PLCs' evolution stages?

• Invention of the First PLC (Modicon 084) in 1986 by Dick Morley and his team. It is the beginning of the PLC technology as a replacement for the traditional automation control system.

• Using ladder logic programming language in the early 1970s. the ladder logic made it easy for both technicians and engineers to design and modify the process control program.

• Development of PLC Hardware between the 1970s and 1980s. the new hardware enables the improvement of the communication interface, memory capacity, and process speed.

• Integration of PLCs in Manufacturing during the 1980s and 1990s where the PLC became widely distributed and considered the standard automatic control system in various industries.

• Combining PLCs with SCADA Systems in the late 1990s enables the remote monitoring, data acquisition, and control of the industrial process through PLC-SCADA systems.

• Adding networking and connectivity capabilities in the 2000s allowed the usage of more options for remote programming and troubleshooting through a special protocol for industrial systems.

• Recently Industry 4.0 and Smart Manufacturing enabled new features like cloud connectivity, data analysis, and preventive maintenance plans.

What are the main 11 applications of the PLCs?

1. Heavy industrial processes like cement, steel, and fertilizer where control all the manufacturing processes starting from the raw materials preparation to the packing plant including the assurance.
2. Traffic Signal Control. PLCs are used in traffic signal control systems to operate traffic lights automatically where they regulate the timing and sequencing of traffic lights based on predefined patterns,
3. CNC Machines. PLCs are integrated into Computer Numerical Control (CNC) machines to automate machining operations like controlling the spindle speed, tool changes, and coolant flow.
4. Batch Processing. PLCs are used in batch processing like chemicals, food production, and pharmaceuticals, to automate the mixing, blending, heating, and cooling processes.
5. HVAC Systems. PLCs are used to automate heating, ventilation, and air conditioning (HVAC) systems in hospitals, and industrial facilities buildings where they control the operation of chillers and boilers, pumps, fans, and dampers to maintain optimal temperature, humidity, and air quality.
6. Conveyor Systems. PLCs can control the operation of the conveyor systems in manufacturing facilities like cement and fertilizer industries to automate material handling, sorting, and packaging processes where PLCs start and stop conveyor belts as well as adjust the speed and direction of the conveyor system.
7. Water Treatment Plants where the PLCs play an important role in automating water treatment processes in water treatment plants and wastewater treatment facilities where PLCs control valves, pumps, filters, and chemical dosing systems.
8. Robotic Welding where PLCs are used to control the movement of robotic arms, welding torches, and positioning devices to ensure accurate welds.
9. Packaging Machines. PLCs are used in foods and other various manufacturing packing machines to control the filling, sealing, and labeling of the product packaging process.
10. Elevator Control Systems. PLCs are used to control and automate the operation of elevators like floor selection, emergency cases, and doors opening and closing where they ensure efficient and smooth operation with maximum safety factors.
11. Material Handling Robot. PLCs are used to control warehouse material handling robots in manufacturing facilities to control and automate tasks like picking, palletizing, packing, and materials transportation. PLCs can also control the movement of robots, gripper functions, and conveyor interactions for material handling optimization.

Summary

Programmable logic control (PLC) is a specialized technology used to automate, control, and monitor industrial processes. It has many advantages over the traditional types of controls such as flexibility, reliability, safety, and cost optimization. That is because of its simplicity and maintenance-free features.

PLCs had evolution stages starting from the invention of the preliminary model (Modicon 084) to the integration with the industry 4.0 passing through ladder diagram programming, hardware development, integration with SCADA systems, and networking capabilities. PLCs are used in