What baud rate does the DFRobot SEN0604 use by default?

9600 bps, 8N1. It is a Modbus-RTU slave; default address 1.

What supply voltage does the DFRobot SEN0604 need?

DC 5–30 V (Low (RS-485 bus-powered class)).

How do I change the DFRobot SEN0604 Modbus address?

Write the device-address register with function code 0x06, one device on the bus at a time, then power-cycle. See the Configuration section above.

Is the DFRobot SEN0604 compatible with the Sankhya platform?

Yes — it is in the Sankhya RS-485 sensor library and the firmware-generation pipeline can produce node firmware for it.

Does the DFRobot SEN0604 measure N-P-K?

The DFRobot SEN0604 reports moisture, temperature, EC, pH, salinity and TDS only — it does not report N-P-K. On the same RS-485 bus, add N-P-K: DFRobot SEN0605.

How many Modbus registers does the DFRobot SEN0604 expose?

This guide documents 15 registers, read with function code 0x03 and written with 0x06 where the register is RW. Documented entries include Soil moisture, Soil temperature, Electrical conductivity, pH, Salinity and TDS.

Can SEN0604 readings be used in a home garden?

Yes. The sensor is industrial in interface and construction, but the dashboard does not impose a minimum farm size.

Are salinity and TDS separate sensing elements?

They are reported outputs tied to the device's conductivity conversion model. They should not be treated as independent laboratory identification of dissolved ions.

Home / Sensors / DFRobot SEN0604

DFRobot · RS-485 sensor

DFRobot

DFRobot SEN0604

DFRobot 4-in-1 — moisture, temp, EC, pH (with salinity/TDS).

✓ Verified for SankhyaMoistureTemperatureECpHSalinityTDSVerification 0.95 · datasheet-confirmed

At a glance

The DFRobot SEN0604 is a 6-in-1 RS-485 soil probe reporting moisture, temperature, EC, pH, salinity and TDS over Modbus-RTU on RS-485 at 9600 bps, 8N1, on DC 5–30 V. This guide documents 15 registers, default Modbus address 1. It does not report N-P-K. For those on the same bus: N-P-K → DFRobot SEN0605. Sankhya firmware profile: DFROBOT_4in1.

Sankhya Farms integration

Six reported values, kept in the same observation record

Sankhya Farms supports the DFRobot SEN0604 with the DFROBOT_4in1 profile. The node polls moisture, signed temperature, EC and pH plus the sensor's salinity and TDS outputs at 9600 baud, then sends them to the free cloud dashboard. Conversion coefficients and calibration registers remain configuration, so a broad register map does not turn into a cluttered chart of unrelated integers.

The sensor can be useful in an orchard, field plot, greenhouse bed, nursery container, landscaped site, home garden or solid hydroponic medium where several root-zone conditions need to be compared. One timeline makes it possible to ask whether a conductivity rise occurred while the medium was drying, whether pH changed after irrigation, or whether a temperature event coincided with a moisture shift. Sankhya can remain a read-only monitoring layer; the presence of AI and automation features does not force a grower to hand control to the platform.

What is not included: SEN0604 does not report N-P-K. Add the SEN0605 or another verified nutrient probe if that is a separate requirement. Compare all 22 profiles.

Value lookup

How do I find each SEN0604 reading?

The main values are moisture at 0000H ×0.1%, signed temperature at 0001H ×0.1 °C, EC at 0002H in µS/cm and pH at 0003H ×0.1. Salinity and TDS are 0007H and 0008H. Later words beginning at 0022H and 0050H are coefficients and calibration values. Sankhya maps the semantic fields rather than charting every register indiscriminately.

Can SEN0604 readings be used in a home garden?: Yes. The sensor is industrial in interface and construction, but the dashboard does not impose a minimum farm size.
Are salinity and TDS separate sensing elements?: They are reported outputs tied to the device's conductivity conversion model. They should not be treated as independent laboratory identification of dissolved ions.

Quick reference

Bus & electrical specs

Protocol

Modbus-RTU over RS-485

Default baud

9600 bps

Serial format

8N1

Function codes

0x03, 0x06

Supply voltage

DC 5–30 V

Power

Low (RS-485 bus-powered class)

Default address

Ingress / housing

IP68

Probe / element

316 stainless steel

Operating temp.

−40 to +80 °C (probe)

Firmware profile

DFROBOT_4in1

Specs sourced from: Official DFRobot wiki (SEN0600–SEN0605 product pages).

Modbus-RTU register map

Function codes 0x03, 0x06 at 9600 bps, 8N1. Data registers are read with 0x03; configuration registers are written with 0x06. PLC column shows the 4xxxx Modbus holding-register convention.

Register	PLC	Parameter	Type	Scale	Unit	R/W	Notes
0000H	40001	Soil moisture	uint16	0.1	%	RO
0001H	40002	Soil temperature	int16	0.1	°C	RO
0002H	40003	Electrical conductivity	uint16	1	uS/cm	RO
0003H	40004	pH	uint16	0.1	pH	RO
0007H	40008	Salinity	uint16	1	mg/L	RO	Reference only.
0008H	40009	TDS	uint16	1	mg/L	RO	Reference only.
0022H	40035	Conductivity temperature coefficient	uint16	0.1	%	RW
0023H	40036	Salinity conversion coefficient	uint16	0.01	—	RW
0024H	40037	TDS conversion coefficient	uint16	0.01	—	RW
0050H	40081	Temperature calibration	int16	0.1	°C	RW
0051H	40082	Moisture calibration	int16	0.1	%	RW
0052H	40083	Conductivity calibration	int16	1	uS/cm	RW
0053H	40084	pH calibration	int16	0.1	pH	RW
07D0H	42001	Device address	uint16	1	—	RW
07D1H	42002	Baud rate	uint16	1	—	RW

Example poll

Worked query

Configuration

Changing address & baud rate

This probe is configured over the same RS-485 bus using Modbus write commands (function code 0x06). Configure one device at a time on the bus.

Set the Modbus slave address by writing register 07D0H (PLC 42001) with function code 0x06.
Set the baud rate by writing register 07D1H (PLC 42002).
Power-cycle the probe after a configuration write for the change to take effect.

Field notes

Notes & caveats

Official map. 4-in-1: moisture+temp+EC+pH.

FAQ

Common questions

What baud rate does the DFRobot SEN0604 use by default?: 9600 bps, 8N1. It is a Modbus-RTU slave; default address 1.
What supply voltage does the DFRobot SEN0604 need?: DC 5–30 V (Low (RS-485 bus-powered class)).
How do I change the DFRobot SEN0604 Modbus address?: Write the device-address register with function code 0x06, one device on the bus at a time, then power-cycle. See the Configuration section above.
Is the DFRobot SEN0604 compatible with the Sankhya platform?: Yes — it is in the Sankhya RS-485 sensor library and the firmware-generation pipeline can produce node firmware for it.
Does the DFRobot SEN0604 measure N-P-K?: The DFRobot SEN0604 reports moisture, temperature, EC, pH, salinity and TDS only — it does not report N-P-K. On the same RS-485 bus, add N-P-K: DFRobot SEN0605.
How many Modbus registers does the DFRobot SEN0604 expose?: This guide documents 15 registers, read with function code 0x03 and written with 0x06 where the register is RW. Documented entries include Soil moisture, Soil temperature, Electrical conductivity, pH, Salinity and TDS.

Alternatives

How this differs from similar models

How the DFRobot SEN0604 compares with the other RS-485 models in the Sankhya library. "Drop-in" means the same parameter set and the same register map, read by the same firmware profile.

Model	Relationship	Measures	Baud	Difference
DFRobot SEN0601	Sibling	Moisture, Temperature, EC, Salinity, TDS	9600	Drops pH.
DFRobot SEN0603	Sibling	EC, pH, Salinity, TDS	9600	Drops moisture and temperature.
DFRobot SEN0602	Sibling	Moisture, Temperature, pH	9600	Drops EC, salinity and TDS.
DFRobot SEN0600	Sibling	Moisture, Temperature	9600	Drops EC, pH, salinity and TDS.

Same family

Related DFRobot sensors

Run this sensor on a Sankhya node

Every sensor on this page is in our RS-485 library. Pick your model, and the firmware-generation pipeline builds the Modbus (or ASCII) polling code for an ESP32-S3 node — no hand-coding the register math.