Understanding Mitsubishi PLC Wiring Diagrams

Programmable Logic Controllers (PLCs) are critical components in industrial automation, controlling everything from manufacturing processes to building systems. Mitsubishi Electric is a prominent player in the PLC market, known for its reliable and versatile PLCs. To harness the power of Mitsubishi PLCs, it's crucial to understand their wiring diagrams thoroughly. In this article, we will provide you with a comprehensive guide to Mitsubishi PLC wiring diagrams, helping you navigate through the intricacies of industrial automation.

Chapter 1: What is a Mitsubishi PLC?

Before diving into wiring diagrams, let's start with the basics. A Mitsubishi PLC is a specialized industrial computer designed to control various machinery and processes. These PLCs are widely used in manufacturing, energy management, and building automation. They consist of a CPU (Central Processing Unit), input and output modules, and communication interfaces.

Chapter 2: Components of a Mitsubishi PLC Wiring Diagram

To understand how to wire a Mitsubishi PLC, it's essential to identify the key components of a typical PLC wiring diagram:

  1. Power Supply: The power supply provides the necessary voltage (usually 24V DC) to run the PLC and its connected devices. Proper power supply connections are critical to the PLC's reliable operation.
  2. CPU Module: The CPU module is the brain of the PLC, responsible for processing logic and making decisions based on input data.
  3. Input Modules: These modules connect to various sensors, switches, and devices, converting their signals into digital or analog data that the CPU can process.
  4. Output Modules: Output modules interface with actuators, relays, and other devices, allowing the PLC to control industrial processes and machinery.
  5. Communication Modules: Some PLCs include communication modules for networking and remote monitoring, enabling data exchange with other systems.

Chapter 3: Understanding Wiring Diagram Symbols

Wiring diagrams use standardized symbols to represent components and connections. Here are some common symbols you'll encounter in Mitsubishi PLC wiring diagrams:

  • Power Supply: Shown as a DC voltage source symbol.
  • CPU Module: Represented as a rectangle with a label indicating the CPU type.
  • Input Modules: Depicted as rectangles with labels indicating the input type (e.g., DI for Digital Input, AI for Analog Input).
  • Output Modules: Shown as rectangles with labels indicating the output type (e.g., DO for Digital Output, AO for Analog Output).
  • Wiring Connections: Lines connecting components indicate the electrical connections. Labels specify wire numbers and signal flow direction.

Chapter 4: Wiring a Mitsubishi PLC

To wire a Mitsubishi PLC effectively, follow these steps:

  1. Power Supply Connection:
    • Connect the positive and negative terminals of the power supply to the PLC's power input terminals.
    • Ensure proper grounding to prevent electrical noise.
  2. Input Module Wiring:
    • Connect sensors, switches, or other input devices to the appropriate input module terminals.
    • Maintain the correct polarity for digital inputs and adhere to voltage and current specifications for analog inputs.
  3. Output Module Wiring:
    • Connect output devices (such as relays, motors, or solenoids) to the output module terminals.
    • Ensure proper voltage and current ratings for digital and analog outputs.
  4. Communication Module (if applicable):
    • Connect communication modules following the manufacturer's guidelines.
    • Configure network settings and protocols as required.
  5. Verify Wiring:
    • Double-check all connections and ensure they match the wiring diagram.
    • Test the PLC to ensure it operates as expected.


Mastering Mitsubishi PLC wiring diagrams is essential for any industrial automation professional. Understanding the components, symbols, and wiring procedures enables you to design and implement efficient control systems. Always refer to the manufacturer's documentation and adhere to safety standards when working with PLCs to ensure safe and reliable operations in industrial settings. Mitsubishi Electric's PLCs offer powerful automation capabilities, and a thorough understanding of their wiring diagrams is a valuable skill for those in the field of industrial automation.


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