LOGO!：A Step-by-Step Guide to Building a Simple Irrigation Control System
Hello everyone, I am an engineer with over ten years of experience in the field of industrial automation. Today, I would like to share an interesting project – using the Siemens LOGO! smart relay to implement a small irrigation control system. This solution is particularly suitable for gardening enthusiasts or those looking to get started with PLCs.
Why Choose LOGO!?
I remember when I first got into automation, I thought PLCs were both expensive and difficult. Until I encountered LOGO!, this “little cutie,” which made me realize that programming can actually be quite simple. The advantages of LOGO! include:
- Affordable price, low entry cost
- Graphical programming, no programming background required
- Compact size, easy to install
- High reliability, suitable for long-term operation
Hardware Preparation
To implement this irrigation system, we need:
- LOGO! Basic Module (recommended version 0BA8 or higher)
- Waterproof temperature and humidity sensor
- Water pump or solenoid valve (12V or 24V)
- Relay module (for controlling the water pump)
- Power supply module (24V DC)
Tip: It is recommended to choose a LOGO! model with a display screen for easier on-site debugging and parameter modification.
System Design Concept
The core functions of this system are:
- Timed watering function
- Soil moisture detection
- Automatic pause on rainy days
- Manual control mode
- Status display
My design philosophy is to ensure that plants receive sufficient water while avoiding overwatering. The system monitors soil moisture in real-time through sensors and implements intelligent irrigation based on time control.
Key Points of Program Implementation
- Timed Control Module
Copy
// Use weekly timer to set watering time
// It is recommended to execute watering between 5:00-6:00 AM
B001 = Weekly Timer（No.1）
On = 5:00
Off = 6:00
- Moisture Control
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// Analog input configuration
AI1 = Soil Moisture（0-10V）
B002 = Analog Threshold（
On = 30% // Start when below 30%
Off = 70% // Stop when above 70%
）
- Main Control Logic
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Q1 = B001 AND B002 AND NOT B003
// B003 is the rainy day detection signal
Tip: When writing the program, be sure to add delay protection to avoid frequent starting and stopping of the water pump.
Practical Application Case
Last year, I applied this solution in a small nursery project. The system has been running for over a year with quite good results:
- Saved over 80% in labor costs
- Reduced water usage by about 30%
- Better plant growth
However, I also encountered some issues, such as:
- Sensor failure due to water ingress
- Pipeline blockage causing abnormal pressure
- Valve jamming that went undetected
Debugging Tips
Based on practical experience, I have summarized a few debugging suggestions:
- First, test without load to confirm logic is correct
- Debug step by step, starting with individual functions
- Set reasonable protection parameters
- Regularly check sensor data
- Retain manual control functionality
Common Problem Solutions
Q: How to prevent sensor failure?
A: Choose waterproof models and perform regular cleaning and maintenance.
Q: What to do if the water pump does not start properly?
A: Check the relay contacts and increase the start delay.
Q: How to handle power outages?
A: It is recommended to install a UPS to ensure data is not lost.
Experience Summary
Working on this project has made me deeply realize that:
- Simple and practical solutions are often the most reliable
- Leaving manual control is very important
- Regular maintenance is the guarantee of system stability
I hope this sharing can inspire everyone. If you are also trying similar projects, feel free to exchange and discuss. The world of automation is vast, and let’s explore and progress together!
Lastly, let me say this: hands-on practice is the best way to learn. Don’t get bogged down by complicated theories; pick up your tools and start trying! I believe you can also create surprising works.