SJ57 SHT30 Industrial Temperature & Humidity Probe
The SJ57 SHT30 Probe is a ruggedized, industrial-grade environmental sensor that combines the high-precision Sensirion SHT30 digital chip with a specialized protective housing and an RS485 Modbus RTU communication interface.
Unlike standard consumer-grade sensors, the SJ57 is specifically engineered for long-term reliability in harsh, dusty, or high-humidity environments such as greenhouses, cold storage, and industrial workshops.
1. The “SJ57” Protective Housing
The standout feature of this probe is its Sintered PE (Polyethylene) Filter Shell:
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Waterproof & Breathable: The porous structure allows water vapor (humidity) to pass through to the sensor while blocking liquid water droplets, preventing short circuits and corrosion.
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Dust & Particle Protection: It acts as a shield against fine dust and airborne contaminants that could otherwise coat the sensor element and cause “sensor drift” or permanent damage.
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High Thermal Conductivity: Despite its protective nature, the housing is designed to minimize thermal lag, ensuring the sensor responds quickly to ambient changes.
2. Technical Specifications
| Feature | Specification |
| Sensing Chip | Original Swiss Sensirion SHT30 |
| Interface | RS485 (Half-Duplex) |
| Protocol | Standard Modbus RTU (Functions 0x03, 0x04) |
| Voltage Input | DC 9V – 36V (Supports 12V/24V industrial systems) |
| Temperature Range | -40°C to +80°C (Standard use) |
| Temp. Accuracy | +/-0.2°C to +/-0.3°C |
| Humidity Range | 0% to 100% RH |
| Humidity Accuracy | +/-2% to +/-3% RH |
| Cable Length | Typically 1 meter (Customizable) |
3. Communication & Integration
Because it uses the RS485 physical layer, this probe excels where I2C or analog sensors fail:
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Long-Distance Wiring: Data can be transmitted reliably over 1,200 meters, making it ideal for large facilities.
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Multi-Device Bus: You can connect multiple SJ57 probes to a single 4-wire bus. Each probe can be assigned a unique Slave ID (Address) between 1 and 247.
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Direct PLC/HMI Compatibility: The Modbus RTU protocol allows for easy integration with industrial controllers (Siemens, Delta, Mitsubishi) and touchscreens (TJC, Nextion, Weinview).
4. Wiring & Installation
The probe typically features a 4-core shielded cable to minimize electromagnetic interference:
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Red (VCC): Power Supply Positive (9–36V DC)
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Black (GND): Power/Signal Ground
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Yellow/White (A+): RS485 Data A
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Blue/Green (B-): RS485 Data B
Pro-Tip for Installation: Always mount the probe with the sensor tip pointing downward. This prevents gravity from pulling condensation into the sensor element and ensures any moisture drains away from the internal electronics.
5. Ideal Applications
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Smart Agriculture: Monitoring soil-top humidity and greenhouse climate.
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Industrial Cold Chain: Temperature tracking in refrigerators and transport containers.
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HVAC Systems: Precision sensing for building automation and air handling units.
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Weather Stations: Outdoor environmental data collection.
