What is PLC? All about PLC - From basic to advanced

1. What is PLC?

1.1. General introduction to PLC

1.2. Definition and history of PLC

1. The programmable logic controller (PLC) was first developed in 1968 by a group of General Motors engineers. They established certain technical standards to ensure that the PLC could be easily programmed and adapted for industrial environments, had a modular structure for easy maintenance and expansion, and had to be compact yet maintain high reliability in industrial manufacturing environments at a competitive cost.
2. The early standards spurred further research and development on the PLC, with both its software and hardware being upgraded. In terms of software, the PLC has been improved to support simple logic instructions, timing, counting, mathematical processing, and even high-speed data and signal processing. In terms of hardware, it has expanded with larger memories, more inputs and outputs, and specialized modules.
3. From early models with only 20 inputs/outputs and a program memory capacity of about 500 steps, PLCs evolved into modular systems that could be easily expanded and upgraded. By 1976, PLCs had the ability to remotely control inputs and outputs through communication techniques. PLCs have been and are an effective solution for industrial automation, helping businesses improve productivity and product quality by replacing outdated technology with advanced automation systems.

1.3. Outstanding advantages of PLC compared to other systems

1. High reliability: PLCs are designed to withstand harsh environmental conditions such as high temperatures, dust, humidity, and vibration. Therefore, they are very reliable and less prone to failure in industrial environments.
2. Easy programming and configuration: PLCs use simple programming languages ​​such as Ladder Logic, Function Block, Structured Text, etc., which makes programming easy and flexible. Users can easily change or expand the system without having to change the hardware.
3. Easy integration: PLCs are capable of connecting and communicating with other devices and systems through a variety of network and communication protocols such as Ethernet, Modbus, Profibus, etc., making integration into existing automation systems easy.
4. Cost effective: Compared to centralized control systems, PLCs are often lower in cost because they do not require complex and expensive hardware. Maintenance and upgrades are also simpler, resulting in long-term cost savings.
5. Expandability: PLCs are expandable in both hardware and software. Users can easily add new input/output modules or features as system needs change.
6. Fast processing speed: PLCs are designed to handle control tasks in real time, with low latency. This is extremely important in process control and manufacturing applications that require quick responses.
7. Safety and security: PLCs have built-in safety features, such as access control and data encryption, to ensure the safety of both the system and data.

2. Structure and main components of PLC

1. It is the heart of the PLC, where all control programs are processed based on input signals and output corresponding signals.
2. The CPU is responsible for scanning programs, performing logic/comparison/counting calculations, and controlling machine operations.

1. Contains control programs, data, and configuration information. PLC memory is usually divided into two types: program memory (storing control logic) and data memory (storing variables, device status).
2. It can include ROM, RAM, and often has additional flash memory to store programs and data when power is lost.

1. Input: receives signals from sensors, switches, and other input devices. Can be digital or analog signals.
2. Output: sends control signals to devices such as motors, valves, indicator lights, and other devices.

1. Provides the power needed for the PLC and its modules to operate.
2. There is usually a circuit that automatically switches between AC and DC power to ensure a stable power supply.

1. Not a necessary part but often used to display information and allow the user to interact directly with the PLC.
2. May include touch screens, buttons, and other indicators.

1. Allows the PLC to connect and communicate with other peripheral devices such as computers, industrial networking systems, or other PLCs.
2. Common protocols include Ethernet, Modbus, Profibus, and CAN.

1. Provides a place to mount all the physical components of the PLC, including the CPU, input/output modules, and other accessories.

3. How PLC programmer works

PLC diagram and operating principle

1. Data acquisition: The PLC begins its work cycle by reading the status of input devices. These inputs can include signals from sensors (such as temperature, pressure), switches, buttons, and other input devices.
2. Input classification: PLCs distinguish between digital inputs (which have two states: on/off) and analog inputs (which have values ​​in a range, such as 0 to 10V).
3. Input signal processing: Before being fed into the program, analog input signals are often converted to digital values ​​for easier processing.

1. Logic Analysis and Processing: PLCs use pre-programmed programs to analyze input signals. This program may include logic, mathematical, and control statements based on input parameters.
2. Decision Making: Based on the program logic, the PLC determines the actions necessary to adjust the output devices.

1. Output Activation: The PLC sends signals to output devices based on the results of the program execution. These output devices can include motors, valves, indicator lights, and other devices.
2. Action Execution: Output devices perform actions such as opening/closing valves, adjusting motor speed, turning on/off heating equipment, etc.

1. Repeat cycle: After completing the cycle from input to output, the PLC starts a new cycle by scanning the input signals again and continuing to execute the program. This cycle repeats continuously and rapidly to ensure timely response to changes in the operating environment.

1. Communication with monitoring systems: In many systems, PLCs also communicate with central monitoring and control systems such as SCADA or HMI, allowing operators to monitor and control the process remotely.

4. Classification of PLC lines on the market

4.1. Basic PLC and Advanced PLC

1. Basic PLCs: Typically used in simple applications with low requirements for complexity and speed. They are suitable for small systems with few I/O points and do not require much in the way of data processing or network integration. Basic PLCs are an economical choice for basic automation needs, such as controlling a single machine or simple processes.
2. Advanced PLCs: Designed for more complex applications that require more expansion modules, network integration, and better data processing capabilities. These PLCs can support hundreds to thousands of I/O points and have advanced communication capabilities with SCADA systems, HMIs, and other control systems. They are often used in large manufacturing plants and complex automation systems.

4.2. Top PLC brands on the market

PLC Siemens

1. Capabilities: Fast calculation, efficient I/O management.
2. Applications: Suitable for medium and large sized systems and production lines.
3. Characteristics: High cost, only suitable for applications with large budgets.

1. Type: Micro PLCs.
2. Function: Supports full range of control commands, including logic, counting, timing, calculation and communication.
3. Supported modules: Includes Digital Input, Digital Output, Analog Input, Analog Output, and many other communication modules.

1. Features: Replaces S7-200, belongs to small PLC type.
2. Application: Used for small machines and production lines.
3. Benefits: Full features, simple programming, low cost, popular in industry.

1. Improvements: Modern version of S7-300.
2. Features: High speed CPU, large I/O expansion capability, support for features such as OPC, Web server.
3. Applications: Can replace S7-300 in applications that need to exploit powerful new features.

1. Features: The most powerful of Siemens PLC lines.
2. Capabilities: Hot-Standby, large I/O management, high processing speed.
3. Applications: Suitable for DCS systems controlling factories and large production lines.
4. Note: High cost, less used than other lines due to initial investment costs.

Buy genuine Siemens PLC at: Amazen Industrial Electrical Equipment

PLC Omron

1. Micro PLC (ZEN) Series:

   • This is a compact, affordable PLC series, suitable for simple applications such as controlling lights, water pumps, or small machines.
   • Easy to program and install.

2. Compact PLC (CP) Series:

   • The CP series offers a wide selection of CPUs, I/Os and expansion modules, suitable for small and medium-sized applications. Popular series include CP1E, CP1L, CP1H and CP2E.

3. Modular PLC (CJ/CS) Series:

   • This is a high-end PLC line, with flexible expansion capabilities, suitable for complex industrial applications.
   • Popular lines such as: CJ1, CJ2, CS1.
     Has strong network connectivity, supports many industrial communication protocols.

4. Machine Automation Controller (NJ/NX):

   The NJ/NX series is a new generation PLC series, integrating motion control, robot control and data processing capabilities.
   • Suitable for high-end automation applications that require high performance and accuracy.
     Popular series such as: NJ, NX1P, NX1, NX7.

For more details, see Omron PLC information at: https://amazen.com.vn/plc/omron.html

PLC LS

1. XGT Series:
   • Including smaller series such as XGK, XGI, XGR.
     • Features:
       High processing performance.
       Flexible expansion capability.
       Supports multiple industrial communication protocols.
       XGR is a redundant system produced by LS based on IEC 42ns/step for speed process control. This product line has up to 32MB memory with a simple interface design, very easy to use.
   • This is LS's high-end PLC series, designed for complex automation applications.
2. XGB Series:
   • This PLC series is suitable for small and medium applications.
     • Compact design, easy to use.
       Features:
       Diverse features.
       Reasonable cost.
       LS PLC XGB series is a compact PLC series, high features, easy to use, convenience and many supporting functions are the 5 important features of the PLC XGB series.
3. MASTER-K Series:
   • LS classic PLC series, used in many industrial applications.
   • High reliability, easy to program.
4. GLOFA-GM Series:
   • This PLC series offers a wide range of CPU and I/O options, suitable for a wide range of applications.
5. XMC Motion Series:
   • LS XMC Motion PLC currently has 2 lines: XMC-E32A, XMC-E32C providing EtherCAT-based position (motion) control functions with high performance, built-in many functions and high technology specialized for numerical control and robots.

Genuine LS PLC programming kit supplier: Amazen Industrial Electrical Equipment

PLC Mitsubishi

1. Number of I/O: 14-60, expandable to 128 I/O.
2. Voltage: 12-24VDC or 100/230VAC.
3. Memory: 8000 steps.
4. Communication: RS485/RS422/RS232, Ethernet, ProfileBus, CC-Link.
5. Features: Supports analog modules, temperature control, position control with maximum output pulse frequency of 100kHz.

1. Number of I/O: 16-128, expandable to 256 I/O.
2. Voltage: 24VDC or 100/230VAC.
3. Memory: 16000 steps.
4. Communication: RS485/RS422/RS232.
5. Features: Enhanced PID processing, basic command execution time 0.08us, support real-time clock.

1. Number of I/O: 10-30, no expansion support.
2. Voltage: 24VDC or 100/240VAC.
3. Memory: 2000 steps.
4. Communication: RS422.
5. Features: Improved high-speed counter, integrated communication card for network communication.

1. Number of I/O: 14-60, expandable to 128 I/O.
2. Voltage: 24VDC or 100/240VAC.
3. Memory: 32000 steps.
4. Communication: RS232, RS485, USB, Ethernet, CAN, CC-Link.
5. Features: Built-in large memory, logic processing in 0.21µs, support for diverse expansion.

1. Number of I/O: 16-128, expandable to 384 I/O.
2. Voltage: 24VDC or 100/240VAC.
3. Memory: 64000 steps.
4. Communication: RS232, RS485, USB, Ethernet, Profibus, CAN, CC-Link.
5. Features: Fast processing speed 0.065µs, bus adapter feature for communication block expansion.

1. Number of I/O: 32-80, expandable.
2. Voltage: 100-240VAC or 24VDC.
3. Memory: 64000 steps.
4. Communication: RS485, Ethernet.
5. Features: Built-in analog support, high-speed pulse input, 200kHz high-speed counter, no data pin required.

PLC Schneider

1. Schneider Electric offers comprehensive PLC solutions, from compact controllers for simple applications to complex automation systems for large industries.
2. Schneider PLCs are renowned for their reliability, high performance and powerful networking capabilities.

1. This is a smart relay line, suitable for simple automation applications such as controlling lights, water pumps, or HVAC systems.
2. Easy to program and install.

1. This PLC series is ideal for simple machine applications.
2. Compact design, reasonable cost, and easy to use.

1. This PLC series offers higher performance and better networking capabilities than the M221.
2. Suitable for more complex machine applications.

1. This PLC series is designed for industrial automation applications that require robust networking capabilities.
2. Supports multiple industrial communication protocols.

1. This PLC series is designed to control complex machines, and applications requiring high performance.

1. This PLC series is a flexible programmable logic controller, suitable for automation applications in the industry. With fast data processing, diverse communication interfaces and highly adaptable expansion modules, the
2. M340 offers high performance and easy integration into the overall system.

1. This is Schneider's high-end PLC series, designed for complex automation applications and requiring high reliability.
2. Extremely high processing performance, strong networking capabilities, and redundancy.

See more information about Schneider PLC at: https://amazen.com.vn/plc/schneider.html

1. Application size and complexity.
2. Number and types of I/O required.
3. Processing speed and performance requirements.
4. Network connectivity and communication with other devices.
5. Budget.

1. Diverse products, suitable for many applications.
2. Powerful features and high reliability.
3. Easy to program and install.
4. Good technical support.

5. Applications of PLC in industry

PLC in manufacturing automation

1. Improve the efficiency and accuracy of production lines.
2. Adjust or change production processes without changing hardware.
3. Help automate complex processes such as assembly, packaging, and quality control.

1. Optimize energy usage and monitor energy supply systems.
2. Automate temperature, pressure and flow control processes in HVAC systems.
3. Reduce energy consumption and improve overall system energy efficiency.

PLC in the automotive industry

1. Automate car manufacturing processes from engine assembly to painting and final inspection.
2. Ensure high production precision, minimize downtime and ensure vehicle quality.

PLC in food industry

1. Control food processing, packaging and storage.
2. Ensure food is produced hygienically and safely.
3. Increase production speed and reduce waste, maintaining product quality and taste.

6. Some notes when choosing PLC

6.1. Requirements for quantity and type of I/O (Input/Output)

1. Determine the number and types of inputs/outputs required for the application.
2. This includes assessing current needs and future expansion possibilities.
3. I/O types include digital input, digital output, analog input, and analog output.

6.2. Processing speed and memory capacity

1. Evaluate the CPU speed and memory capacity of the PLC to ensure that they are capable of handling the complexity of the application effectively.
2. Applications that require rapid data processing or complex algorithms will require PLCs with higher processing speeds and memory capacity.

6.3. Scalability

1. Consider the scalability of the PLC to accommodate future system growth.
2. This includes the ability to expand the number of I/Os, add function modules, and connect to other devices.

6.4. Network connectivity

1. Evaluate the PLC's networking capabilities, including supported communication protocols (e.g. Ethernet, Modbus, Profibus).
2. This is especially important for integrated automation systems or applications that require remote monitoring and control.

6.5. Programming software

1. Consider the PLC programming software, including ease of use, features, and compatibility with other programming tools.
2. A good programming software will help reduce the time and cost of application development.

6.6. Reliability and durability

1. Choose a PLC with high reliability to ensure continuous operation of the system.
2. This factor can be assessed based on the manufacturer's maintenance and repair history.

6.7. Expense

1. Consider the cost of the PLC, including the cost of purchasing the equipment, the cost of programming, and the cost of maintenance.
2. Choose a PLC that fits within your project budget.

1. Make sure the manufacturer or distributor provides good technical support, including documentation, training, and maintenance services.

6.9. Operating environment

1. Consider the PLC's operating environment, including temperature, humidity, and vibration levels.
2. Choose a PLC that can operate reliably in harsh environments.

6.10. Brands and suppliers

1. You should choose PLC brands that have a good reputation in the market, and suppliers that can provide you with the best support.

7. The Future of PLC in the Digital Age

7.1. Digital transformation in industry

• The future of PLCs is tied to the integration of advanced technologies such as IoT, AI, cloud computing and big data. This allows PLCs to not only control machines, but also make intelligent decisions, optimize production processes and predict maintenance.
• Increasingly important role:

7.2. The Evolution of PLC Combined with IoT

7.3. The Impact of AI and Total Automation on PLCs

8. Conclude