Irrigation system with time and humidity sensor

Description

This function block enables fully automated control of an irrigation system – including manual start/stop, time control, and humidity sensor control. The modular code in Structured Control Language (SCL) is ready for immediate use in the Siemens TIA Portal and is perfectly suited for gardens, greenhouses, or industrial applications requiring water.

Note: All modules are designed exclusively as a learning and optimization basis and are not approved for live operation. System modules, in particular, must be finally tested and commissioned by qualified personnel before productive use.

How it works

Manual commands are at the top of the priority list: Anyone who wants to start or stop the system using a button can do so at any time – the current state is set immediately.

If the automatic function is activated, the system starts once a day at exactly the set time – all by itself. The running time is controlled by an internal timer, after which the system stops automatically.

Additionally, a moisture sensor monitors the soil. If the moisture level falls below the set threshold, the system begins watering—assuming it was inactive beforehand. Once the soil is sufficiently moist, watering stops. If the sensor delivers incorrect values (e.g., a wire break), the module detects this immediately and issues a corresponding error message.

Technical details

• Manual operation: Edge triggers set or clear the operating status immediately.
• Time automatic: Starts daily at the defined time, with a tolerance of 1 second.
• Irrigation duration: Controlled by a TON timer.
• Humidity monitoring: Comparison of the sensor value with the limit value during inactivity.
• Safety: Sensor errors (e.g. wire break) are reliably detected and reported.
• Outputs: Clearly defined TRUE/FALSE signals for pump, valve and status indicators.

Possible applications

Whether it's a hobby garden, greenhouse, or industrial facility – this module provides reliable irrigation exactly when it's needed. It's also ideal for training purposes, demonstrating how time, process value, and fault logic interact in the PLC.

compatibility

• Siemens S7-1200 and S7-1500
• TIA Portal from version V13
• Recommendation: V16 or higher for HMI and PLCSIM simulation

Scope of delivery

You'll receive a clean .scl file with all input/output declarations, timer parameters, triggers, and thresholds, humidity limit, and alarm logic. The download link is available immediately after purchase.

Support

I am happy to help – for example with:

• adjusting the time windows or humidity logic
• the extension to include weather data or multiple irrigation zones
• the visualization on your HMI

Simply contact us by email or directly through our shop support – together we’ll get your system ready for next summer.