What baud rate does the DFRobot SEN0603 use by default?

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

What supply voltage does the DFRobot SEN0603 need?

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

How do I change the DFRobot SEN0603 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 SEN0603 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.

What does the DFRobot SEN0603 not measure?

The DFRobot SEN0603 reports EC, pH, salinity and TDS only — it does not report moisture, temperature and N-P-K. On the same RS-485 bus, add moisture: DFRobot SEN0601; temperature: DFRobot SEN0601; N-P-K: DFRobot SEN0605.

How many Modbus registers does the DFRobot SEN0603 expose?

This guide documents 11 registers, read with function code 0x03 and written with 0x06 where the register is RW. Documented entries include Electrical conductivity, pH, Salinity, TDS, Conductivity temperature coefficient and Salinity conversion coefficient.

Why does the SEN0603 dashboard not show moisture?

Because the physical model does not report it. A faithful integration preserves an absent parameter instead of manufacturing a value.

Yes. The dashboard may display or export only pH even though the node also records the other supported channels for context.

Home / Sensors / DFRobot SEN0603

DFRobot · RS-485 sensor

DFRobot

DFRobot SEN0603

DFRobot EC + pH monitoring probe (with salinity/TDS).

✓ Verified for SankhyaECpHSalinityTDSVerification 0.95 · datasheet-confirmed

At a glance

The DFRobot SEN0603 is a 4-in-1 RS-485 soil probe reporting EC, pH, salinity and TDS over Modbus-RTU on RS-485 at 9600 bps, 8N1, on DC 5–30 V. This guide documents 11 registers, default Modbus address 1. It does not report moisture, temperature and N-P-K. For those on the same bus: moisture → DFRobot SEN0601; temperature → DFRobot SEN0601. Sankhya firmware profile: DFROBOT_ECpH.

Sankhya Farms integration

A focused EC and pH dashboard profile

The DFRobot SEN0603 is not a moisture sensor with extra chemistry channels. Sankhya Farms handles it through the DFROBOT_ECpH profile, collecting EC, pH, salinity and TDS at 9600 baud and sending those named values to the free cloud dashboard. Moisture and temperature remain absent rather than being filled with zeroes or inferred from another DFRobot map.

A focused chemistry probe can be useful in a soil or substrate trial, greenhouse bed, nursery, home-garden experiment, salinity study or any installation where EC and pH are already the primary observations. It may share an RS-485 bus with a separate moisture-temperature probe when physical separation or replacement flexibility matters. Salinity and TDS are derived through the instrument's conductivity model. For hydroponic reservoirs, confirm that the exact sensing assembly is liquid-rated; otherwise use a documented water-quality pH/EC transmitter, which Sankhya can support after its protocol is added.

Free dashboard support: the node turns the SEN0603 register family into four labelled time series. Pair it with a moisture and temperature model if those values are required.

Value lookup

Which SEN0603 registers hold EC and pH?

Electrical conductivity is 0002H in µS/cm and pH is 0003H ×0.1. Salinity and TDS are at 0007H and 0008H. Conversion coefficients appear at 0022H–0024H, and calibration offsets at 0052H and 0053H. Sankhya separates live values from coefficient and calibration words before upload.

Why does the SEN0603 dashboard not show moisture?: Because the physical model does not report it. A faithful integration preserves an absent parameter instead of manufacturing a value.
Can I track pH only?: Yes. The dashboard may display or export only pH even though the node also records the other supported channels for context.

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_ECpH

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
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
0008H	40009	TDS	uint16	1	mg/L	RO
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
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. EC+pH only, no moisture or temperature.

FAQ

Common questions

What baud rate does the DFRobot SEN0603 use by default?: 9600 bps, 8N1. It is a Modbus-RTU slave; default address 1.
What supply voltage does the DFRobot SEN0603 need?: DC 5–30 V (Low (RS-485 bus-powered class)).
How do I change the DFRobot SEN0603 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 SEN0603 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.
What does the DFRobot SEN0603 not measure?: The DFRobot SEN0603 reports EC, pH, salinity and TDS only — it does not report moisture, temperature and N-P-K. On the same RS-485 bus, add moisture: DFRobot SEN0601; temperature: DFRobot SEN0601; N-P-K: DFRobot SEN0605.
How many Modbus registers does the DFRobot SEN0603 expose?: This guide documents 11 registers, read with function code 0x03 and written with 0x06 where the register is RW. Documented entries include Electrical conductivity, pH, Salinity, TDS, Conductivity temperature coefficient and Salinity conversion coefficient.

Alternatives

How this differs from similar models

How the DFRobot SEN0603 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 SEN0604	Sibling	Moisture, Temperature, EC, pH, Salinity, TDS	9600	Adds moisture and temperature.
DFRobot SEN0601	Sibling	Moisture, Temperature, EC, Salinity, TDS	9600	Adds moisture and temperature, drops pH.
DFRobot SEN0602	Sibling	Moisture, Temperature, pH	9600	Adds moisture and temperature, drops EC, salinity and TDS.
DFRobot SEN0600	Sibling	Moisture, Temperature	9600	Adds moisture and temperature, 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.