HD3910.x Soil Volumetric Water Content

Installation

1. 1Wire the Delta OHM HD3910.x probe to the RS-485 port on your ModbusCloud gateway (MCG or MLP series), observing correct A/B and GND connections.
2. 2Set the Modbus slave address on the HD3910.x probe according to the manufacturer instructions, ensuring it does not conflict with other devices on the bus.
3. 3Confirm that the baud rate on the probe is set to 9600, matching the default configuration of this template.
4. 4Import the HD3910.x template in the ModbusCloud platform and assign it to the correct gateway and Modbus address.
5. 5Verify that VWC, soil temperature, and dielectric permittivity values appear correctly on the dashboard after the first polling cycle.
6. 6If multiple probes are installed on the same RS-485 bus, assign unique Modbus addresses to each and add a separate template instance per probe.

Things to watch for

01

Why are my VWC or temperature readings showing values that seem 10 times too high or too low?

The raw register values for VWC and temperature are scaled by a factor of 10. The template applies this scaling automatically. If you see unexpected values, check that you are using the correct template version and that no additional scaling is applied in your dashboard configuration.

02

What baud rate should I use for the HD3910.x probes?

The default baud rate is 9600. Both the probe and the ModbusCloud gateway must be set to the same baud rate. If you have changed the baud rate on the probe, update the gateway configuration accordingly.

03

Can I connect multiple HD3910.x probes on one RS-485 bus?

Yes. Assign a unique Modbus slave address to each probe and create a separate template instance in ModbusCloud for each address. Ensure proper RS-485 bus termination if the cable run is long.

04

How do I interpret the status byte register?

The status byte indicates the operational state of the probe. Refer to the Delta OHM HD3910.x documentation for the specific bit definitions. A non-zero status byte typically signals a measurement issue or sensor fault.

Registers (5)

5 read / 0 write

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