PLC Finals PDF

Lesson 5: Introduction to Programmable Logic Controllers (PLC) Lesson Objectives: 1. Understand the concept and significance of PLCs in industrial automation. 2. Learn the main components and functionalities of PLC systems. 3. Distinguish between hardware, firmware, and software in a PLC...

Lesson 5: Introduction to Programmable Logic Controllers (PLC) Lesson Objectives: 1. Understand the concept and significance of PLCs in industrial automation. 2. Learn the main components and functionalities of PLC systems. 3. Distinguish between hardware, firmware, and software in a PLC context. Lesson 5.1: Introduction to PLCs Definition A Programmable Logic Controller (PLC) is a digital computer designed specifically for industrial automation to monitor and control various processes. Background PLCs were introduced in the late 1960s by Bedford Associates with the creation of the Modicon device. Modicon 084: The first PLC device, a milestone in industrial automation, replaced electromechanical relays with solid-state digital computers. Why PLCs? PLCs streamline control processes, making them faster, more reliable, and easier to program. They are essential in controlling complex industrial processes, such as assembly lines and chemical production. Main Components of a PLC 1. CPU (Central Processing Unit): ○ The brain of the PLC. ○ Receives input signals, processes programmed logic/calculations, and sends output signals to control devices (e.g., motors, bulbs). 2. Memory: ○ Stores data, programs, and information. ○ Two types: ROM (Read-Only Memory): Stores permanent data like operating systems and firmware (non-volatile). RAM (Random Access Memory): Temporary storage for data and variables during PLC operation. 3. Power Supply: ○ Provides the necessary power for the PLC system to function. 4. Input/Output (I/O) Modules: ○ Interfaces that connect the PLC to external devices.  ○ Input modules receive signals from sensors, switches, etc. ○ Output modules send signals to actuators, motors, etc. Key Terms Hardware vs. Firmware vs. Software Aspect Hardware Firmware Software Definition Physical components Specialized software Programs that provide of a computer or PLC. embedded in hardware. user interaction. Examples CPU, hard disk, BIOS, UEFI (Extensible Internet browsers, monitor, keyboard, Firmware Interface). operating systems, etc. mouse. User Directly visible. Operates behind the Interfaces directly with Interaction scenes. the user. Update Rarely updated. Infrequently updated to fix Frequently updated for Frequency bugs or improve new features and fixes. functionality. Firmware Examples 1. BIOS (Basic Input/Output System): ○ Runs at startup, verifies hardware functionality, and loads the OS into RAM. 2. EFI (Extensible Firmware Interface): ○ New standard developed by Intel, replacing traditional BIOS. ○ Features: Eliminates the boot loader. Enhances security by allowing vendors to create drivers resistant to reverse engineering. Provides a lightweight shell environment at boot. ○ Now a standard known as UEFI (Unified Extensible Firmware Interface). Significance of PLCs in Automation PLCs enable automation across industries, including: Assembly Lines: Controlling machinery for efficient production. Chemical Processes: Managing complex operations with precision. Electrical Systems: Ensuring minimal power loss in devices. Mechanical Systems: Supporting high-temperature operations like jet engines. Civil Engineering: Reinforcing strong materials for infrastructure. Main Components of a PLC 1. CPU (Central Processing Unit) The "brain" of the PLC, responsible for processing inputs, executing the program, and controlling outputs. 2. Memory RAM (Random Access Memory): ○ Used for both reading and writing data. ○ Information in RAM can be edited or changed during PLC operation. ROM (Read-Only Memory): ○ Stores permanent data like the PLC’s operating system and firmware. 3. Input/Output (I/O) Modules Interface the PLC with the external environment. Types of I/O Modules: ○ Digital I/O Modules: Handle on/off signals. ○ Analog I/O Modules: Handle variable signals (e.g., temperature, pressure). ○ Some I/O modules include built-in safety features to protect workers and equipment. 4. Power Supply Converts input power into the voltages required by the PLC’s internal components. Provides isolated VDC (Volts Direct Current) to power input circuits and indicators. VDC is measured in volts and powers devices like batteries, electronic circuits, and motors. PLC Operation A PLC operates in a continuous loop consisting of four basic steps: 1. Input Scan: Detects the state of all input devices connected to the PLC. 2. Program Scan: Executes the user-created program logic. 3. Output Scan: Energizes or de-energizes output devices based on program results. 4. Housekeeping: Handles internal diagnostics, communication with programming terminals, and maintenance tasks. Programming Terminal A text-based Command-Line Interface (CLI) used to interact with the PLC. Functions of a terminal include: ○ Navigating directories. ○ Copying files. ○ Running programs. ○ Managing processes.  ○ Accessing remote servers and virtual machines. Example PLC Operation: Controlling an Electric Motor with a Button Process Steps: 1. Connect the button to the PLC’s input module. 2. Program the PLC to recognize signals from the button. 3. When the button is pressed, the PLC activates the output module, starting the motor. 4. When the button is released, the PLC stops the motor. This basic operation illustrates how PLCs monitor input signals and adjust output devices accordingly. Advantages of Using PLCs 1. Increased Productivity: ○ Automates repetitive tasks, reducing human intervention. 2. Improved Efficiency and Cost Savings: ○ Optimizes processes, reduces waste, energy consumption, and downtime. 3. Flexibility: ○ Easily programmed or reprogrammed to adapt to new processes or products. 4. Accuracy: ○ Executes precise calculations, reducing errors. 5. Safety: ○ Ensures machines and processes operate safely and reliably. Disadvantages of Using PLCs 1. Security and Compatibility: ○ Vulnerable to cyberattacks and compatibility issues with devices from different manufacturers. 2. Complexity: ○ Programming and troubleshooting require expertise. 3. Cost: ○ High initial costs, depending on the system's sophistication. 4. Maintenance: ○ Regular upkeep is required to ensure reliability. 5. Environmental Sensitivity: ○ Susceptible to noise, vibration, temperature, and moisture. 6. Potential Failures: ○ Risks include module failure, power outages, bad network connections, overheating, and electromagnetic interference. Major PLC Manufacturers Siemens Allen-Bradley (Rockwell Automation) Mitsubishi Electric Schneider Electric (Modicon) Omron ABB Honeywell Delta Electronics Lesson 5.2: PLC Operating Systems, Application Programs, Scanning, Addressing, Basic Instructions PLC Operating Systems Operating Systems Used in PLCs PLC Operating System Allen-Bradley PLC5 Microware OS-9 Allen-Bradley ControlLogix VxWorks Emerson DeltaV VxWorks Schneider Modicon Quantum VxWorks Yokogawa FA-M3 Linux Wago 750 Linux PLC Reference Platform QNX Neutrino Siemens SIMATIC WinAC RTX Microsoft Windows PLCs Overview Allen-Bradley PLC-5 Overview: A series of PLCs by Rockwell Automation for industrial control applications. Key Characteristics: ○ High-performance: Fast processing for demanding applications. ○ Modularity: Customizable and expandable platform. ○ Robustness: Rugged construction for harsh environments. ○ Networking: Supports various communication protocols. ○ Legacy Status: Still functional but largely replaced by newer platforms like ControlLogix. Applications: ○ Manufacturing (assembly lines, packaging). ○ Process Control (oil & gas, water treatment). ○ Discrete Manufacturing (robotics, machine tools). Key Components: ○ Processor Module: Executes control programs. ○ I/O Modules: Connects sensors, actuators, and HMIs. ○ Power Supply: Provides system power. ○ Chassis: Houses all components. Programming: Programmed using RSLogix 5. Note: ControlLogix is recommended for new projects due to enhanced features and performance. Allen-Bradley ControlLogix Overview: A series of PACs by Rockwell Automation, designed for advanced industrial automation. Key Functions: ○ Programmable Logic Control (PLC). ○ Motion Control. ○ Process Control. ○ Safety and Networking. Key Features: ○ Modular Design: Expandable with I/O, communication, and motion modules. ○ High-Speed Performance: Handles fast control loops and large processes. ○ Integration: Supports other Rockwell products, third-party devices, and Ethernet/IP. ○ Reliability: Trusted for critical applications. Applications: Automotive, food & beverage, oil & gas, pharmaceuticals, etc. Emerson DeltaV Overview: A digital automation system for process industries, emphasizing flexibility, scalability, and integration. Key Features: ○ Distributed Control System (DCS): Centralized or decentralized plant control. ○ Scalable and Modular: Adapts to small or large operations. ○ Integrated Control and Safety: Handles normal and safety-critical tasks. ○ Advanced Control: Features like Model Predictive Control (MPC). ○ Flexible I/O Architecture: Adapts to plant requirements. ○ User-Friendly Interface: Real-time visualizations and alarms. ○ Redundancy: High availability with built-in redundancy. ○ Integrated Asset Management: Tools for predictive maintenance. Benefits: ○ Increased efficiency and productivity. ○ Enhanced safety. ○ Cost-effective scalability. ○ Seamless integration with Emerson and third-party systems. Applications: Oil & gas, chemicals, pharmaceuticals, power generation, food & beverage. Schneider Modicon Quantum The Schneider Modicon Quantum is a modular, high-performance PLC system designed for industrial automation and control applications. It is part of the Modicon family, a pioneer in PLC technology, and is specifically built for large-scale, complex automation tasks in industries like manufacturing, energy, water treatment, oil and gas, and transportation. Key Features 1. Modular Architecture:  ○ Highly customizable system with interchangeable components (CPU, I/O modules, power supplies, communication modules). ○ Flexible and scalable for diverse applications. 2. High-Speed Processing: ○ Supports real-time control and high-speed data handling. 3. Distributed I/O: ○ Reduces wiring by placing I/O modules close to field devices. ○ Improves system efficiency and performance. 4. Redundancy & High Availability: ○ Offers redundancy in processors, power supplies, and communication networks. ○ Ensures minimal downtime for mission-critical applications. 5. Advanced Communication Capabilities: ○ Supports Ethernet/IP, Modbus TCP, Modbus RTU, Profibus, and more. ○ Seamlessly integrates with SCADA and supervisory systems. 6. Safety Integration: ○ Manages both standard and safety-related functions in compliance with IEC 61508 and ISO 13849. 7. Programming and Configuration: ○ Uses Unity Pro software, offering multiple programming languages (Ladder Logic, Structured Text, FBD). Benefits Scalability & Flexibility: Easily adapts to both small and large systems. High Reliability: Engineered for demanding environments with robust, fault-tolerant designs. Optimized Performance: Handles complex tasks with minimal latency. Advanced Control: Enables predictive maintenance, diagnostics, and real-time monitoring. Global Integration: Compatible with industry standards and diverse platforms. Applications Manufacturing Automation: Production lines, process control, and quality management. Energy & Utilities: Power generation, water treatment, and electrical substations. Oil & Gas: Refining, pipeline monitoring, and offshore platforms. Transportation: Railways, traffic systems, and logistics automation. Yokogawa FA-M3 Overview The Yokogawa FA-M3 is a high-performance PLC system tailored for industrial automation and process control. It is part of Yokogawa's FA (Factory Automation) series, designed to deliver precision, speed, and reliability in industries like manufacturing, oil and gas, pharmaceuticals, food and beverage, and power generation. Key Features 1. Modular and Scalable Architecture: ○ Tailor-made system with add-on modules for I/O, communication, and specialized functions. 2. High-Speed Processing: ○ Fast response times and real-time decision-making for precision applications like motion control. 3. Advanced Communication: ○ Supports protocols like Ethernet/IP, Modbus, CC-Link, and Profibus. ○ Includes web-based monitoring and remote access. 4. Integrated Safety Functions: ○ Compliance with IEC 61508 and ISO 13849 ensures safe operation. 5. Flexible I/O Options: ○ Distributed I/O and various modules for analog, digital, and high-speed data. 6. Real-Time Diagnostics: ○ Advanced tools for quick troubleshooting and system reliability. 7. Redundancy: ○ Ensures high availability with redundant CPUs and power supplies. 8. Cloud and IoT Integration: ○ Supports modern IoT platforms for predictive maintenance and data analytics. Benefits High Performance: Real-time control for demanding automation tasks. Modular Flexibility: Scalable to meet changing operational needs. Enhanced Safety: Integrated safety features ensure compliance and reliability. Scalability: Fits both small and large-scale operations. Integration Capabilities: Easily connects to existing and future systems. Applications Manufacturing: Assembly lines, material handling, and packaging. Oil & Gas: Refining, pipelines, and offshore platforms. Power Generation: Turbine control, power distribution, and automation. Pharmaceuticals: Precision control, compliance, and data logging. Water & Wastewater: Efficient water treatment operations. Food & Beverage: Reliable processing and inventory management. WAGO 750 Series Overview The WAGO 750 Series is a versatile and modular I/O system designed for industrial automation applications. Part of the WAGO-I/O-SYSTEM, it offers flexible, scalable solutions for distributed control systems (DCS), programmable logic control (PLC), and other automation tasks across industries like manufacturing, energy, water treatment, transportation, and more. Key Features 1. Modular Design: ○ Flexible architecture with various I/O, communication, and power modules that can be easily mixed and matched. ○ Scalable, allowing users to add or replace modules based on application needs. 2. Wide Range of I/O Modules: ○ Digital I/O: For discrete devices (e.g., sensors, actuators). ○ Analog I/O: For continuous signals such as temperature, pressure, and flow. ○ Specialized I/O: Modules for counters, thermocouples, RTDs, etc. 3. Communication Protocols: ○ Supports a variety of industrial protocols, including: Modbus TCP/IP and Modbus RTU PROFIBUS DP Ethernet/IP CANopen BACnet (building automation) KNX (building management) MQTT (IoT applications) 4. Engineering Software Support: ○ WAGO e!COCKPIT: A user-friendly engineering software for configuration, programming, and visualization. ○ CODESYS: A widely-used PLC programming environment that supports multiple IEC 61131-3 languages (Ladder Logic, Function Block Diagram, Structured Text). 5. Flexible Power Supply Options: ○ Operates with various power supply options, some with redundancy for high availability in critical systems. 6. Distributed Control System (DCS): ○ Modular design allows distributed control, minimizing wiring complexity and enabling efficient control in large, distributed systems. 7. Compact Design: ○ Ideal for installations with space constraints or remote setups, such as control cabinets. 8. Ease of Integration: ○ Supports standard industrial communication protocols and can integrate easily into existing control systems, SCADA systems, or IoT platforms. 9. Reliability and Durability: ○ Built with high-quality components to withstand harsh industrial environments (temperature, vibration, electrical noise). 10. Distributed I/O Functionality: I/O modules can be placed close to field devices, reducing long-distance wiring and improving signal integrity. Benefits Scalability: Easily expandable and adaptable to changing system requirements. Flexibility: A broad range of I/O modules and communication protocols for diverse applications. Integration: Supports integration with PLCs, SCADA, IoT platforms, and other industrial systems. Cost-Effective: Modular design reduces initial setup and long-term operational costs. Reliability: High uptime and durability in demanding industrial conditions. Ease of Configuration: Tools like e!COCKPIT and CODESYS simplify configuration and programming, reducing development time. Typical Applications Industrial Automation: Used in controlling machines, processes, and manufacturing lines (e.g., automotive, food processing, packaging). Building Automation: Applied in HVAC, lighting, and security systems in commercial and smart buildings. Energy Management: Utilized in renewable energy systems, power plants, and energy grids for monitoring and control. Water and Wastewater Treatment: Controls pumps, valves, and equipment in treatment plants. OEM Equipment: Commonly used in Original Equipment Manufacturers' systems for controlling specific processes. Transportation & Infrastructure: Deployed in railway, metro, and transportation systems for operational control and monitoring. PLC Reference Platform The PLC Reference Platform is a comprehensive toolset for developing industrial control systems. It includes: 1. ISaGRAF PLC Firmware – Scalable software for integrated automation solutions. 2. KPA EtherCAT Master Stack – High-speed communication for real-time control and EtherCAT networks. 3. QNX Neutrino RTOS – A microkernel OS for embedded, mission-critical applications. 4. QorIQ P1025 Tower Module – High-performance microprocessor for networking applications. 5. ISaGRAF 6 Workbench – Modular development environment for creating automation programs. 6. KPA EtherCAT Studio – Tool for managing EtherCAT networks and automating tasks. This platform enables the development of real-time, high-performance automation systems suitable for industries like manufacturing, robotics, and energy. Siemens SIMATIC WinAC RTX Siemens SIMATIC WinAC RTX provides real-time software for PC-based automation, ensuring deterministic processing for industrial control applications. Key features include: 1. WinLC RTX – PLC functionality within a PC-based system. 2. Venturcom RTX – Real-time extensions for Windows NT for deterministic control. 3. Computing Software – ActiveX controls for system communication.  4. Tool Manager – Utility for managing automation tools. WinAC RTX is ideal for applications requiring precise, real-time control, such as in process automation and machine control. PLC Operating Systems 1. Microware OS-9 ○ Type: Real-Time Operating System (RTOS) ○ Features: Modular software structure for speed and protection. Logical memory modules for self-contained programs. Customizable exception handling. Multimedia Application User Interface (MAUI) for easy multimedia integration. ○ Platform Support: Motorola 6809, ARM/XScale, MIPS, PowerPC, Intel x86, and others. ○ Applications: Medical, automotive, industrial automation. 2. VxWorks ○ Type: High-performance RTOS ○ Features: Real-time, deterministic, and high-performance. Scalable from microcontrollers to multi-core systems. Built for mission-critical systems with reliability, safety, and security. ○ Applications: Aerospace, defense, medical devices, industrial automation, automotive. 3. Linux ○ Type: Open-source OS ○ Features: Stability, security, and highly customizable. Open-source with a large developer community. Unix-like structure, supports a wide range of hardware. ○ Applications: Servers, desktops, embedded systems, supercomputers. 4. QNX Neutrino RTOS ○ Type: Real-time OS with microkernel architecture ○ Features: Microkernel for security and fault-tolerance. Real-time, scalable, and reliable with deterministic performance. Security features like memory protection and encryption. ○ Applications: Automotive (ADAS), medical devices, industrial automation, aerospace, telecommunications. 5. Microsoft Windows ○ Type: GUI-based OS ○ Features: User-friendly graphical interface. Dominant in personal computing with vast software compatibility. Regular updates and versions like Windows 10, 11, and server editions. ○ Applications: Personal computing, business, gaming, education. PLC Application Programs 1. Omron PLC  ○ Provides many functions and controls for small equipment and production lines. ○ Includes an online AutoUpdate system for free updates. 2. Allen-Bradley PLC Programming ○ Offers training in RSLogix 5000, used for programming Allen-Bradley PLCs, a leading manufacturer in the PLC industry. 3. MapleLogic ○ A configuration software that allows users to create control solutions using preferred programming languages. Common PLC Applications Industrial Applications: ○ Process control functions ○ Manufacturing production ○ Mobile automation ○ Monitoring machine tools ○ Robotic automation systems ○ Food processing systems ○ Paper industry Everyday Applications: ○ Road traffic signals ○ Automatic car washes ○ Elevators ○ Automatic doors ○ Conveyor belts ○ Roller coasters Popular PLC Programming Languages 1. Ladder Diagram (LD) ○ Most common in the U.S. ○ Resembles an electrical schematic, using symbolic notation to show the logical relationships between inputs and outputs. ○ Widely used for automating repetitive machine tasks and sequences. ○ Common Applications: Material handling conveyor systems Ball mill lubrication systems Cement batching Beverage bottling and labeling 2. Sequential Function Charts (SFC) 3. Function Block Diagram (FBD) 4. Structured Text (ST) 5. Instruction List (IL) Ladder Logic (LD) Overview: A graphical language expressing logic operations using a diagram resembling relay logic circuits, making it easy for engineers and electricians to transition from electrical circuits to PLC programming.  Key Features: ○ Graphics-Based Interface: Drag-and-drop functionality for quickly formulating control logic. ○ Troubleshooting: Ladder diagrams make it easier to troubleshoot by visually showing the flow of logic. ○ Basic Structure: Rails: Vertical lines representing the start and end of the logic. Rungs: Horizontal lines representing the logical connections. Symbols: Represent inputs (e.g., switches), outputs (e.g., motors), and logic operations. How to Draw Ladder Logic Diagrams 1. Rails: Vertical lines at both ends, representing the active power supply. 2. Rungs: Horizontal lines connecting the rails, each representing a control logic step. 3. Inputs: Control actions like a push button or limit switch, symbolized as normally open (NO) or normally closed (NC) contacts. 4. Outputs: Devices such as motors or solenoids, symbolized as relay coils. 5. Logic Expressions: Define the control operations by combining inputs and outputs. 6. Address Notation/Tag Names: Represent memory addressing for PLC components. 7. Comments: Descriptive text for clarity and easier understanding of the logic. Essential Parts of a Ladder Logic Diagram Rails: Represent the power supply. Rungs: Represent logical operations or sequences. Inputs/Outputs: Represent the physical controls and devices involved in the automation process. Logic Expressions: Define the control logic and relationships. Address Notation & Tag Names: Used for memory addressing. Comments: Essential for understanding the code logic. How Ladder Logic Works Ladder logic is a graphical programming language used in PLCs to automate industrial processes. It simulates relay logic with graphical symbols, such as contacts and coils, but without the extensive physical wiring. Input/Output Devices: Inputs and outputs are wired to the PLC, and ladder logic decides which outputs to activate based on input signals. Simplified Wiring: Unlike traditional relay logic, ladder logic programs the control actions, requiring only wiring for inputs and outputs. Basic Components: Includes symbols for relays, timers, counters, and PID controllers, all programmed into the PLC. Reading Ladder Logic Ladder logic is read from left to right and top to bottom, with each rung representing a logical operation that evaluates input states to control outputs. Binary Concept Ladder logic works on binary principles: TRUE/FALSE, 1/0, On/Off. Inputs and outputs are represented by Normally Open (NO) and Normally Closed (NC) contacts, each reflecting binary states. Normally Open (NO) Contacts NO contact: TRUE when the event is active (current flows). FALSE when the event is inactive (current is blocked). Normally Closed (NC) Contacts NC contact: Inverse of NO, TRUE when the event is inactive (current flows). FALSE when the event is active (current is blocked). Key Logic Functions NOT (inverted logic) IF, THEN, AND, OR How Ladder Logic is Executed In a PLC, ladder logic is executed through a series of steps: 1. Input Reading: All input states (such as sensors or switches) are read and stored in memory. 2. Scan Through Rungs: The PLC scans each rung of the ladder logic, evaluating from left to right, top to bottom. 3. Output Execution: After evaluating all rungs, the PLC executes the results, activating or deactivating outputs accordingly. Basic Ladder Logic Functions Normally Open (NO) and Normally Closed (NC) Contacts: Represent the state (TRUE or FALSE) of events, and work together with logic functions to determine actions. Binary and Logic Concepts Ladder logic works with binary concepts: true/false, on/off, 1/0. These concepts guide the logic functions that drive automation. Ladder Logic IF, THEN Functions For an input event (A), the output (Y) follows the logic: IF A = TRUE, THEN Y = TRUE IF A = FALSE, THEN Y = FALSE Ladder Logic AND Function AND: All inputs must be TRUE for the output to be TRUE. If any input is FALSE, the output is FALSE. The inputs are arranged in series, like a direct connection in a circuit. Ladder Logic OR Function OR: If any input is TRUE, the output is TRUE. Inputs are arranged in parallel, allowing any TRUE input to trigger the output. Latching and Unlatching Latching: Keeps an output on even after the initiating input is removed (e.g., keeping a motor running after a button is released). Unlatching: Resets the output state when another condition or button is triggered. Example: Pump Control Latching: When a start button (PB1) is pressed, the pump (5.00) turns on and remains on even after the button is released. Unlatching: A stop button (PB4) will turn the pump off, resetting the state. Summary Ladder logic executes in a systematic process where inputs trigger evaluations, logic functions (AND, OR, NOT) determine actions, and outputs are activated accordingly. It also includes techniques like latching and unlatching to maintain control states without constant input signals. Sequential Function Chart (SFC) A Sequential Function Chart (SFC) is a graphical programming language used for designing and programming Programmable Logic Controllers (PLCs). It models sequential control systems where each step is active or inactive, making it ideal for managing complex processes in industrial automation. Key Features of SFC 1. Steps and Transitions: ○ Steps: Represent different states of a process. ○ Transitions: Connect steps, allowing control to flow when conditions are met. 2. Graphic Symbols: ○ Visual elements like steps, actions, qualifiers, and transitions form the chart. 3. Visual Representation: ○ Similar to flowcharts, SFCs break down large processes into manageable components. How SFC Works 1. Steps: Represent states or operations (e.g., filling water in a washing machine). 2. Transitions: Conditional checks required to move between steps (e.g., "water level reached"). 3. Outputs: Correspond to actions triggered during each step (e.g., start motor). Rules for SFC Design Every transition condition must lie between two steps. A step must separate two consecutive transition conditions. Example: Washing Machine Operation Steps: Fill water → Wash → Rinse → Spin. Transitions: Water full → Washing complete → Rinsing complete → Spinning complete. Outputs: Control actions for valves, motors, and pumps. SFC diagrams can also be converted into ladder logic, where each rung represents a step and associated logic conditions. Parallel and Selective Branching 1. Selective Branching: ○ Only one branch can proceed based on transition conditions. 2. Parallel Branching: ○ Multiple branches execute simultaneously if the transition condition is met. ○ Represented by parallel horizontal lines in the diagram. Function Block Diagram (FBD) A Function Block Diagram (FBD) is another graphical PLC programming language where functions are interconnected to form processes. Key Features of FBD 1. Graphical Representation: ○ Resembles high-level flowcharts. 2. Function Blocks: ○ Modular components that reduce redundant code. ○ Can contain small or large logic sections. 3. Parallel Execution: ○ Functions can run simultaneously but may execute at different rates. Example: Camera Triggering A function block for triggering a camera might include: Input: Start acquisition.  Outputs: Error flag, inspection results. This block is reusable for multiple cameras. Structured Text (ST) Structured Text (ST) is a high-level text-based PLC programming language resembling traditional languages like Python or Java. Key Features of ST Syntax: Uses statements separated by semicolons, written in block structures. Advantages: ○ Easy for non-PLC programmers to learn. ○ Suitable for large, complex projects. ○ Efficient memory use. Instruction List (IL) Instruction List (IL) is a low-level programming language for PLCs, similar to assembly language. Key Features of IL 1. Syntax: ○ Instructions written line by line. ○ Each contains an operator and operands. 2. Operators: ○ LD (Load): Loads values into the accumulator. ○ ST (Store): Saves results to the accumulator. ○ Compare & Jump: Conditional executions or loops. 3. Standardization: ○ XML format standardized by PLCopen. Summary SFC: Visualizes sequential processes. FBD: Focuses on reusable graphical blocks. ST: Offers high-level, text-based programming. IL: A low-level, assembly-like language.