Short answer
Publication date: April 15, 2025
Agricultural automation must do more than receive remote commands. It should react safely to field conditions. A weak internet connection should not stop irrigation, allow a pump to run dry, or prevent a greenhouse protection mechanism from reacting to high wind. A serious smart-farming project therefore requires local control, sensor validation, and safety layers rather than only a mobile button for opening a valve.
NetRelay combines four digital inputs, four relay outputs, Ethernet, Wi-Fi, PoE, and 7–28 V DC power for small and medium agricultural projects. Supported external analog modules can connect soil-moisture, temperature, light, pressure, or wind sensors. An optional DS3231 RTC helps time-based tasks continue when NTP or internet access is unavailable.
How does sensor-based irrigation work?
In a basic scenario, a valve or pump command is generated when soil moisture falls below a threshold. A pump should not start from one measurement alone. The value should remain low for a defined duration, water level should be sufficient, the pump fault contact should be inactive, and the permitted irrigation schedule should be checked.
Local event logic can combine these conditions. NetRelay should not drive a motor directly. Its relay should command a suitable contactor within a panel that includes thermal, phase, and dry-run protection. Digital inputs can read low level, high level, pump fault, and manual/automatic selection contacts.
What happens when the internet is unavailable?
The expected behavior must be defined before deployment. NetRelay can execute local rules without mandatory cloud access. The RTC preserves scheduling, while local sensors and contacts provide the information needed for control decisions.
When central communication is available, MQTT can send telemetry and equipment states to a server. Users can review history, update thresholds, or issue authorized manual commands. During an outage, the device can continue with a safe local program. When connectivity returns, current status can be reported. An optional MicroSD module may support local recording requirements.
Greenhouse protection and environmental control
Beyond irrigation, greenhouses need temperature, ventilation, shading, and wind protection. If temperature remains above a threshold, an auxiliary fan or window-control circuit can be triggered. High wind may move opening systems to a safe position. Light or sunrise/sunset conditions can control supplemental lighting.
Mechanical limit switches, motor protection, and manual intervention must remain available. NetRelay is not the safety controller of a moving system; it is an automation layer that sends commands to a properly designed power and safety circuit. The required safe state after sensor failure should be defined during engineering.
Managing several fields or greenhouses
Devices at different locations can make outbound MQTT connections to a central broker. Instead of opening ports at every site, they can publish soil moisture, valve state, pump fault, tank level, and connectivity information to one dashboard.
Projects can also exchange selected sensor information between devices, but remote commands require authorization, state verification, timeouts, and a safe default condition. Communication loss must never leave a pump or actuator in an uncontrolled state.
How should savings be calculated?
ROI should not be calculated from water consumption alone. Include staff travel, irrigation at the wrong time, delayed pump-fault detection, crop stress, and energy use.
A pilot may begin with one valve group or greenhouse. Record irrigation duration, water use, pump runtime, site visits, alarms, and crop conditions. Compare with the traditional process during a similar period. Weather and crop types vary, so decisions should use a meaningful production period instead of a few days of data.
When is NetRelay suitable?
NetRelay is a strong candidate when four inputs and four outputs are sufficient for valves, pumps, level contacts, alarms, and several environmental sensors. Large irrigation networks, many valves, precision fertigation, hard real-time control, or safety-class processes may require a PLC or RTU as the primary controller. NetRelay can still support telemetry and remote communication.
Before purchase, define sensor output types, contactors, power supply, network coverage, local rules, and manual backup procedures. Share the field layout, pump and valve list, sensors, and required scenarios with the NetRelay technical team to design a realistic project.
Sensor selection and field validation
Soil sensors can behave differently across soil types. Review measurement principle, power, output, and corrosion resistance. Compare readings under dry, ideal, and excessively wet field conditions. If one point does not represent the area, use several sensors or zone-based control.
Protect temperature and humidity sensors from direct sunlight and place wind sensors away from turbulent structures. Long analog cables may require suitable converters, shielded wiring, or field modules. Define a safe response for disconnected sensors and implausible values.
Managing irrigation zones
Four relay outputs can operate several zones through suitable valve circuits or contactors. If pump capacity cannot support all valves, run zones sequentially. Define minimum and maximum duration, waiting time, and daily limits.
A valve-open command does not prove water flow. Critical projects should use a flow or pressure contact. No flow after a command should create a valve, pump, or source alarm. Flow while a valve appears closed may indicate leakage.
Power and field supply
PoE can combine power and data where network cabling reaches a greenhouse or technical room. The 7–28 V DC input supports regulated field or battery systems. Solar-powered sites require an energy budget covering batteries, modem consumption, seasonal conditions, and autonomy.
Lightning, long cables, and pump motors create surge risk. Use suitable surge protection, grounding, fuses, enclosure rating, and cable separation. Outdoor installations need an appropriate protected cabinet.
Maintenance and manual operation
Agriculture must not stop completely after an automation failure. Keep manual valve and pump controls and train users on switching modes. Inspect sensors, cables, moisture, and corrosion at the start of each season.
Alarm history reveals recurring sensor, thermal, low-level, and communication faults. Maintenance can plan visits and spare parts around the most common problems.
Increasing value through data
Control alone is not enough. Soil moisture, irrigation duration, pump runtime, and weather data help identify zones with higher water demand. MQTT data can be reported in custom software or platforms such as Node-RED.
A sales proposal should describe measurable answers: Which zone irrigated longest? How many low-tank alarms occurred? How many pump hours and site visits were recorded? These outputs support continued investment.
Cybersecurity and remote access
Prefer outbound MQTT or VPN to direct router port forwarding. Use unique users and topic permissions. Remote pump commands require role-based access, timeouts, and state verification.
A central command must never override an active low-level or fault safety contact. Store command and user audit records.
Discovery and quotation
Prepare the field layout, zones, valve voltage, pump and contactor data, water source, level sensors, internet, power, and expected local behavior. Do not quote analog integration before sensor output compatibility is confirmed.
The solution package may include NetRelay, modules, sensors, panel components, enclosure, communications, installation, dashboard, commissioning, and training. Seasonal maintenance and remote support can be offered separately.
Frequently asked questions
Does it work without a mobile application?
Yes. Local rules can run essential tasks. Mobile or web interfaces support monitoring, settings, and authorized intervention.
Can irrigation stop when rain begins?
A suitable rain sensor or validated central data can be included. Avoid basing a critical local decision on one internet data source.
How many valves can be controlled?
There are four relay outputs. Pump and alarm outputs reduce the number available for valves. Larger systems may use multiple devices or a PLC/RTU.
Where should the pilot begin?
Choose one high-consumption or difficult-to-reach zone, collect baseline data, and monitor a meaningful growing period.
A 60-day pilot plan
First monitor sensor data and pump runtime without changing the current irrigation process. This creates a baseline. Next, control one irrigation zone through NetRelay while an operator validates every automatic action. Then test safety conditions such as tank level, pump fault, and flow confirmation.
Record sensor deviation, false alarms, communication outages, manual interventions, water use, and energy runtime. Include rainfall and temperature differences. Reduced water use is not success if crop health or quality declines.
Why does user training matter?
Field staff must understand the consequences of bypassing a sensor, running a relay manually, and returning to automatic mode. Label panels and wiring clearly and display emergency manual procedures. Prevent unauthorized remote pump commands.
At the end of the season, review sensor calibration, valve cycles, pump hours, and alarms. These records improve next season's irrigation and maintenance budget. NetRelay then becomes a decision data source rather than only a remote controller.
What should the project achieve?
A successful system should not force growers to watch more screens. It should request attention only for meaningful conditions. Automatic actions must be field-validated, alarms actionable, and manual operation always available. Water or energy savings should be measured without harming crop health.
Plan for next season's sensors and zones, not only today's valves. If four inputs and four outputs will not support growth, evaluate centrally managed multiple devices or a PLC/RTU architecture from the beginning. This prevents a successful pilot from becoming a dead end.
Final engineering review
Before acceptance, test sensor disconnection, low-water protection, pump fault, communication loss, power recovery, and manual override. Document the expected relay state for every failure. Deliver wiring diagrams, calibration notes, user permissions, and seasonal maintenance procedures. These tests are essential because a system that works during normal weather may behave differently during heat, storms, or low-water conditions. A documented failure response protects both crops and equipment and gives the grower confidence to expand the pilot.