PLC

1. Background During a recent safety inspection organized by the Municipal Emergency Management Bureau, one of the reviewing experts insisted that enterprises should add an automatic (emergency) shutdown function in the Distributed Control System (DCS) and configure a corresponding software button on the operator interface. As a participant in this inspection, I raised an objection. […]

Industrial automation relies heavily on robust communication protocols to ensure that devices and control systems work seamlessly together. Among the most widely adopted are Modbus TCP/IP and Profinet. While both leverage Ethernet as their physical layer, their design philosophies, performance characteristics, and application scenarios differ significantly. 1. Origins and Basic Concepts Modbus TCP/IP Originally developed

Programmable Logic Controllers (PLCs) are at the core of industrial automation. Among all supply voltages, 24V DC has become the global standard. This choice is not accidental—it is the result of careful consideration of safety, stability, electromagnetic compatibility, energy efficiency, universality, and cost-effectiveness. 1. Enhanced Safety Safety is the top priority in industrial environments. 24V

In industrial safety and control systems, emergency stop (E-stop) buttons play a critical role in protecting personnel and equipment from harm in the event of an urgent situation. E-stop buttons, often featuring protective covers, are designed to halt machinery immediately when pressed. Whether or not these protective covers should be locked or sealed is a

1. Introduction Industrial Control Systems (ICS) are the backbone of modern industrial production. Their architecture is designed with multiple layers to ensure efficiency, reliability, and stability. This document provides a structured overview of ICS architecture, communication networks, redundancy and security mechanisms, and future development trends. 2. Three-Tier Architecture of ICS 2.1 Field Control Layer —

Abstract In Modbus communication systems based on RS-485, termination resistors are often mentioned as a means of improving signal integrity. However, whether they are always required depends on several technical factors such as cable length, baud rate, and network topology. This document explains the principles, application scenarios, and practical guidelines for deciding when to use

In industrial processes, ensuring safety and preventing catastrophic failures are paramount. Safety Instrumented Systems (SIS) and their associated functions and assessments, such as Safety Instrumented Functions (SIF) and Safety Integrity Levels (SIL), play a critical role in managing and mitigating risk. Here, we’ll discuss these terms in detail, including the distinctions between them and their

Programmable Logic Controllers (PLCs) are designed to operate reliably in industrial environments, but proper installation practices are critical to ensure long-term stability, safety, and maintainability. This document summarizes the key requirements for PLC installation, covering environmental conditions, grounding, cabinet setup, commissioning, redundancy testing, program backup, and software maintenance. 1. Environmental Requirements Enclosure: Install PLCs in

1. Introduction In industrial electrical control systems, the concepts of self-locking, interlocking, and mutual locking are fundamental. Although similar in terminology, each has distinct logic, application, and purpose. This document provides a structured comparison of these three control methods, with definitions, working principles, typical applications, and schematic diagrams. 2. Self-Locking (Hold-On Circuit) 2.1 Definition Self-locking

In industrial process automation, the 4-20mA signal is one of the most widely used standards for transmitting analog data from sensors and transmitters to control systems. This signal range, where 4mA typically represents the zero or minimum of a process variable and 20mA represents the maximum, allows control systems to monitor and manage a wide