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Industrial pH Meter/ Sensor MODBUS-RTU RS485 & 0-2V Analog Voltage (S-pH-01B), with waterproof aviation connector

This industrial-grade MODBUS-RTU RS485 pH meter/sensor features ATC, low-power-consumption, high integration. It can be widely used in monitoring pH levels in soil and water applications such as agriculture, gardening, horticulture, swimming pools, scientific experiments, and other environmental monitoring scenarios. Comes with a waterproof aviation connector, it's convenient to use without the fuss of wiring.




Version 1 of this pH sensor supports RS485 protocol and 4~20mA analog current, which is now retired, and replaced by this current one: Version 2, supporting RS485 protocol and 0~2V analog voltage. 
This Industrial pH Sensor comes in two versions. The main difference is in the cable connector. Please choose the version that best suits your needs: 
(1) S-pH-01B: with a waterproof aviation connector. This version saves you time in deployment as you won't have to use screws to connect the cable to the data logger. And it can be used with SenseCAP Sensor Hub 4G Data Logger instantly with ease.
(2) S-pH-01A: with hook-up wires.


Please send an email to sensecap[at]seeed[dot]cc to request any technical support for this product.


  • High performance: high accuracy, fast response, good repeatability
  • Universal protocol: MODBUS RS-485 or 4~20mA current
  • Wide-range power supply: 3.6V ~ 30V
  • Robustness: suitable to be immersed in soil or water for a long time
  • Maintainance-Free: advanced junction design, no clogging
  • Durable: anti-corrosion, automatic temperature compensation
  • User-friendly: Easy to install and integrate

A pH meter measures the hydrogen-ion activity in water-based solutions, indicating its acidity or basicity expressed as pH. (Wikipedia: pH Meter). pH level is an important indicator in many scenarios, especially in monitoring soil conditions and water quality. A pH sensor is widely used in farming, gardening, hydroponics, aquaponics, swimming pools and spas, sewage treatment, education, environmental monitoring, and many other applications.

This pH sensor (S-pH-01B) is designed with industry standards and equipped with a waterproof aviation connector. It adopts international advanced solid dielectric and large-area polytetrafluoroethylene liquid junction, which is not easy to block and convenient for maintenance. It's designed with ATC (automatic temperature compensation), making sure the data is accurate regardless of the temperature changes. This pH Sensor is IP65 rated, waterproof in a tight seal, capable of withstanding long-term constant use in professional application scenarios.
This pH Sensor comes with a MODBUS-RTU RS485 serial communications protocol or 4~20mA current output. It can be easily connected to and integrated with other devices such as data-loggers, controllers, and displays, etc. This cost-effective pH sensor features low-power consumption, compact size, portability, high integration, making it widely applicable in both indoor and outdoor environments.


Range 0 ~ 14pH
Accuracy ± 0.1 pH
Resolution 0.01 pH
General Parameters
Product Model S-pH-01A
Output Interface Analog Voltage 0-2V (Output resistance ~0ohm) RS-485 MODBUS-RTU
Power Supply 3.9-30V/DC 3.9-30V/DC
Power Consumption [email protected] DC [email protected] DC
Start-up time  < 2 seconds
pH Measurement
High impedance and isolated input;
Range: 0 - 14PH,
Resolution: 0.01PH,
Accuracy: +/- 0.1PH;
Can be used for a solution or semi-solid substrate
Temperature Measurement
Range: - 40~80°C,
Resolution: 0.1°C,
Accuracy: +/-0.5°C
IP Rating

Electrode: IP68;

Transmitter: IP65

Operating Temperature -40℃ ~ 85℃

Electrode: 3/4"NPT screw threads;

Transmitter: Mounting hole

Cable Length
Power and Signal Cable:2 meters (Customizable)
Electrode Cable: 5 meters
Electrode: Width*Diameter 160*30mm; 3/4"NPT screw threads
Transmitter: 140mm*65mm*50mm



  • Agriculture: greenhouse, aquaponics, hydroponics, and crop Plantation, etc.
  • Animal Husbandry: pasture, grassland, and meadow
  • Forestry and Horticulture
  • Sewage Treatment
  • Swimming Pools and Spas
  • Scientific Experiments
  • Educational Projects
  • Other environmental monitoring scenarios 


Wiring Diagram


Please refer to the user manual for more details about the wiring diagram. 

Probe Dimensions


Q:            Is it factory calibrated? How to calibrate?

Yes, the device is fully calibrated prior to shipment from the factory.

About calibration, please refer to the document:

Q:       Why is the temperature output from the sensor inaccurate?
A: PH electrode itself has no temperature sensor, the temperature is the plate temperature sensor; If necessary, you can access the NTC (10K, 3950) thermistor temperature sensor.

Q:     Can the sensor be used in soil? How to install?

Yes, Yes, the principle is still to measure the pH in the soil moisture, so it will be affected by the soil moisture, and the drier the soil, the greater the error.

Installation method: Dig out a pit, fill the pit with some water, stir the soil into a slurry, and then place the sensor glass probe. Be careful not to overexert yourself and avoid hard objects such as stones, otherwise the probe will be damaged.


HSCODE 9025800090
USHSCODE 9031808070
EUHSCODE 9013101000
RoHS 1



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