Hardware selection is very important when you try to develop projects where sensors, actuators and PLC´s must talk each other. For this project, with chosen the following equipment:
- PLC: Any PLC from IndustrialShields is a good option. We have chosen the M-Duino PLC Arduino 21 I/Os Analog/Digital because we think it has different communication options to be communicated with other systems (Ethernet, RS232, I2C…).
- Panel PC: For this project, we are going to visualize and control our installation with the HummTouch 10.1” Linux panel pc.
- Humidity sensor: Probably, when you try to develop an application like we are trying to, the most important selection is the sensor itself. There are a lot of humidity sensors available around the market completely compatible with Arduino based hardware. We´ve chosen the SHT10 sensor from Adafruit because it includes a temperature sensor as well, it comes with an intermetal mesh encasing, which is weatherproof and because it is designed to be submersible in water.
- Others: A relay to activate the irrigation system, a 24Vdc power supply, a good enclosure to protect the equipment and cables are important things to keep in mind too.
To develop the project, the first thing to do is to ensure that we have the proper software and libraries. As we are going to use the SHT10 sensor, we will use the SHT1x library that you can download in the following link: https://github.com/practicalarduino/SHT1x. SHT10 uses a two wire communication interface similar to I2C. As usual, we will use the Arduino IDE to develop the software. You can download it here: http://www.arduino.cc/en/Main/Software. You can see the code in the following file: Key benefits There are a lot of benefits to implement a humidity control in an irrigation system. Let´s see the most important:
- Saves Time: Automation does the job for you, so you can go on holidays knowing that your flowers will be maintained when you come back.
- Saves Money: No more water wasted, automation guarantees efficiency: water is used when is needed.
- Improves Growth: An irrigiation system guarantees flowers waterd with proper amount of water. In a reasonable time, you will have a greener garden.