Step-by-Step Guide to Building a Smart Curtain Control System – Practical Sharing of Mitsubishi FX Series PLC

Hello everyone, I am Lao Wang, an electrical engineer with 15 years of experience in industrial automation. Today, I would like to share a home automation project I recently completed – a smart curtain control system based on the Mitsubishi FX2N PLC. This project is not only practical but also helps those who want to get started with PLCs to quickly grasp the basics.

Why Choose PLC for Smart Curtains?

To be honest, I initially considered using a microcontroller or Raspberry Pi for this implementation. However, considering the stability and anti-interference capabilities of PLCs, along with the fact that I had an idle FX2N at home, I decided to use it for this project. The advantages of using a PLC for curtain control include:

• Stable and reliable, long operating time
• Simple wiring, easy maintenance
• Strong functional scalability
• Can integrate more home automation features

Hardware Preparation

1. One Mitsubishi FX2N-32MR PLC
2. 24V power supply
3. Two limit switches
4. DC geared motor (12V/24V is acceptable)
5. Motor driver module
6. Two push buttons
7. One light sensor

Tip: When selecting a motor, ensure that the torque is sufficient. It is recommended to choose one with an encoder for more accurate positioning. My first attempt failed because the motor torque was too low, resulting in the curtain not moving.

System Design Concept

The core functions of the entire system include:

1. Manual control: Control the opening/closing of the curtain via buttons
2. Automatic control: Adjust based on light intensity
3. Timed control: Set opening and closing times
4. Anti-pinch protection: Timeout/overcurrent protection

System Block Diagram

Copy

Light Sensor ──┐
            │
Timed Input ──┐ │
           │ │
Manual Button ──┼─┼── PLC Controller ── Motor Driver ── Curtain Motor
           │ 
Limit Switch ──┘

PLC Program Implementation

Let’s take a look at the core code section (recommended to bookmark):

awk copy

LD X000        // Open curtain button
OR M8000       // Automatic mode flag
ANI Y001       // Not in closed state
ANI T0         // Timer not activated
OUT Y000       // Start opening curtain

LD X001        // Close curtain button
ORI M8001      // Automatic mode flag  
ANI Y000       // Not in open state
ANI T0         // Timer not activated
OUT Y001       // Start closing curtain

LD X002        // Reached open limit
OR X003        // Reached close limit
OR T0          // Delay protection
RST Y000       // Stop opening curtain
RST Y001       // Stop closing curtain

LD Y000        // Curtain opening in progress
OR Y001        // Curtain closing in progress
TMR T0 K300    // Set 15 seconds protection time

Would you like me to explain or break down this code?

Practical Tips

1. Wiring Recommendations

• It is best to use shielded cables for all signal lines
• Keep power lines and signal lines separated
• Using normally closed contacts for limit switches is safer

1. Debugging Key Points

• Test manual control first
• Then debug automatic functions
• Finally optimize control parameters

I encountered a problem with the motor running in reverse during debugging, and later found that the driver wiring was incorrect. This reminds us to carefully check connections during wiring.

Function Expansion

After stabilizing the system debugging, I added the following features:

1. Mobile APP control (requires an additional communication module)
2. Automatic window closing on rainy days (integrating a raindrop sensor)
3. Room temperature linkage (in conjunction with air conditioning control)

Common Issues and Solutions

1. Motor does not turn

• Check power supply voltage
• Confirm driver working status
• Test if limit switches are functioning normally

1. Unstable operation

• Check grounding conditions
• Identify interference sources
• Adjust control parameters

1. Inaccurate positioning

• Calibrate limit switches
• Check mechanical structure
• Consider adding an encoder

Experience Summary

Working on this project made me deeply realize that in the field of home automation, the reliability of industrial-grade products indeed has its unique advantages. Although the initial investment is relatively high, it is very worthwhile in the long run.

Finally, I hope this sharing can inspire friends who are preparing to undertake similar projects. If anyone encounters problems during practice, feel free to discuss and exchange ideas. Let’s learn and improve together through practice!

This concludes my sharing. If you find it helpful, don’t forget to save and bookmark it! Feel free to discuss any questions at any time.