NBL-S-TMC-7 7-in-1 Soil Sensor with RS485 Modbus

The NBL-S-TMC-7 7-in-1 soil sensor integrates seven soil parameters into one probe: soil temperature, moisture, electrical conductivity (EC), pH, nitrogen (N), phosphorus (P) and potassium (K).

The sensor uses RS485 Modbus RTU communication and a DC 5–24V power supply, allowing connection to compatible PLCs, data loggers, RTUs and agricultural IoT gateways. It is designed for applications where several soil parameters need to be collected from the same monitoring point using one probe and one communication interface.

The temperature, moisture and EC channels are suitable for routine field monitoring. The integrated NPK and pH channels should be treated as field reference values: NPK values are generated from soil electrical characteristics using empirical coefficients, while the integrated pH channel has lower accuracy than a dedicated glass-electrode pH sensor.

What Does the 7-in-1 Soil Sensor Measure?

Important: The specified NPK accuracy is a sensor specification under defined test conditions and should not be interpreted as laboratory-grade accuracy for absolute nitrogen, phosphorus or potassium concentration in all soils.

NBL-S-TMC-7 Technical Specifications

Why Use a 7-in-1 Multi-Parameter Soil Sensor?

Installing several separate soil sensors at the same point increases the number of probes, cables, mounting positions and RS485 addresses required by the monitoring system. The NBL-S-TMC-7 combines seven output channels into one probe and one Modbus connection.

How the Soil Moisture Measurement Works

The moisture channel measures changes in the dielectric characteristics of the soil. Because the dielectric properties of water differ significantly from dry soil components, the sensor can use this relationship to estimate soil moisture content.

For repeatable results, the probes must maintain close contact with the surrounding soil. Air gaps, loose soil around the electrodes, stones and inconsistent installation can affect the reading.

Understanding the NPK Reference Values

The integrated N, P and K channels do not directly perform laboratory chemical analysis of nitrogen, phosphorus and potassium.

The sensor measures soil electrical characteristics and applies empirical conversion coefficients to generate corresponding N, P and K reference values. Soil moisture, conductivity, salinity, fertilizer concentration, soil texture and other field conditions can therefore influence the displayed values.

Understanding the Integrated Soil pH Value

The pH channel in the NBL-S-TMC-7 is intended mainly for field reference and trend monitoring. Its specified accuracy is ±1 pH, so it should not be positioned as a high-accuracy laboratory pH measurement instrument.

For projects where pH accuracy is important, use adedicated glass-electrode soil pH sensorinstead of relying only on the integrated pH channel.

RS485 Modbus RTU Communication

The 7-in-1 soil sensor with RS485 Modbus can connect to compatible PLCs, RTUs, data loggers and IoT gateways. All seven parameters can be read in one Modbus request.

Modbus Register Map

Modbus Read Example

For a sensor with device address 01, the following command reads all seven parameters:

The example response corresponds to:

Temperature: 27.6°C  •  Moisture: 32.6%  •  EC: 75 µS/cm
pH: 7.22  •  N: 8 mg/kg  •  P: 8 mg/kg  •  K: 21 mg/kg

RS485 Wiring

When multiple RS485 soil sensors share one bus, assign a unique Modbus address to each sensor and configure the data logger with an appropriate communication interval.

Quick Measurement and Buried Installation

The NBL-S-TMC-7 can be used for rapid field measurements or installed in the soil for longer-term monitoring. Correct probe-to-soil contact is important in both methods.

Quick Measurement

Choose a representative measurement point and remove stones or other hard objects from the insertion area. Insert the sensor vertically into the soil so the probe is fully surrounded by soil.

Do not repeatedly move the sensor from side to side after insertion. Movement can create air gaps around the probes and reduce contact with the soil. For a small sampling area, several measurements can be taken and compared rather than relying on one point.

Buried Monitoring

For continuous monitoring, dig a pit to the required measurement depth and insert the probe horizontally into the undisturbed side wall. Refill and compact the soil carefully so that the probes maintain close contact with the surrounding soil.

After the installation has stabilized, the sensor can be connected to the monitoring system for continuous data collection over days, months or longer according to project requirements.

Installation Precautions

Agricultural IoT System Integration

7-in-1 Soil Sensor → RS485 Modbus RTU → Data Logger / PLC / IoT Gateway → 4G / Ethernet / LoRaWAN → Cloud Platform or Private Server

The NBL-S-TMC-7 itself provides RS485 measurement data. Remote 4G, Ethernet, Wi-Fi, LoRaWAN, MQTT or HTTP communication requires a compatible data logger or gateway and is not built directly into the soil probe.

7-in-1 Soil Sensor Applications

Thismulti-parameter agricultural soil sensoris suitable for field and IoT projects where several soil measurements need to be collected from one location. The integrated NPK and pH channels are most appropriate for reference and trend monitoring rather than laboratory-equivalent chemical analysis.

Precision Agriculture  •  Smart Irrigation  •  Greenhouse Monitoring  •  Horticulture
Research Plots  •  Grassland & Pasture  •  Soil Trend Monitoring  •  Agricultural IoT

7-in-1 vs 8-in-1 Soil Sensor

If a separate salinity measurement is required, see the8-in-1 integrated soil sensor.

7-in-1 Integrated Sensor vs Dedicated Soil Sensors

7-in-1 Soil Sensor FAQ

Q1. What seven parameters does the NBL-S-TMC-7 measure?

A1. It provides soil temperature, moisture, electrical conductivity, pH, nitrogen, phosphorus and potassium.

Q2. Does the 7-in-1 soil sensor measure salinity?

A2. The NBL-S-TMC-7 does not provide a separate salinity channel. Select the 8-in-1 configuration when a separate salinity measurement is required.

Q3. Are the NPK readings equivalent to laboratory soil analysis?

A3. No. The NPK channels use soil electrical characteristics and empirical coefficients to produce reference values. Laboratory chemical analysis should be used when actual nutrient concentration is required.

Q4. How accurate is the integrated pH measurement?

A4. The specified pH accuracy is ±1 pH. The integrated channel is therefore more suitable for field reference and trend monitoring. For higher pH accuracy, use a dedicated glass-electrode soil pH sensor.

Q5. Does the soil sensor support RS485 Modbus RTU?

A5. Yes. It uses RS485 Modbus RTU at 9600 bps and provides registers for all seven measurement parameters.

Q6. Can all seven parameters be read in one Modbus request?

A6. Yes. Starting from register 0x0000, seven consecutive registers contain temperature, moisture, EC, pH, N, P and K data.

Q7. Can several 7-in-1 soil sensors connect to one data logger?

A7. Yes. Each RS485 sensor should use a unique Modbus address, and the data logger should use suitable polling intervals and power distribution.

Q8. Can the sensor remain buried for continuous monitoring?

A8. Yes. The manual describes a buried installation method for continuous monitoring. Correct soil contact and protection from physical damage remain important.

Q9. Does the sensor have built-in 4G or LoRaWAN?

A9. No. The sensor provides RS485 Modbus data. 4G, Ethernet, Wi-Fi or LoRaWAN communication requires a compatible data logger or IoT gateway.

Q10. What information is required for a quotation?

A10. Provide the required quantity, cable length, installation method, number of monitoring points, power supply and the PLC, data logger or IoT gateway that will receive the RS485 data. If salinity or higher-accuracy pH measurement is required, include that requirement before model selection.

NBL-S-TMC-7 7-in-1 Soil Sensor Instruction Manual

NBL-S-TMC-7-7-in-1-Soil-Sensor-Instruction-Manual.pdf

Request a 7-in-1 Soil Sensor Quotation

For quotation and model selection, provide the required quantity, cable length, number of monitoring points, installation method, power supply and receiving PLC, data logger or IoT gateway.

If the project requires a separate salinity channel, higher-accuracy glass-electrode pH measurement, portable sampling, cloud transmission or private-server integration, include these requirements so the appropriate soil sensor and data-acquisition configuration can be selected.