1 Product Introduction****

The DAQ-GP-PS485 Pressure Sensor is a high-performance pressure transmitter developed by Shanghai DAQ-IOT Technology Co., Ltd. It utilizes a high-precision piezoresistive sensing element as the core measurement component. Each sensor undergoes automated computer-based testing and is precisely calibrated using advanced laser trimming technology to achieve zero-point and sensitivity temperature compensation over a wide temperature range.

The integrated signal conditioning and amplification circuit converts the sensor output into a standard output signal, fully leveraging the advantages of the sensing element. As a result, the pressure/level transmitter delivers outstanding performance and reliability in demanding industrial environments.

Featuring excellent resistance to electromagnetic interference, overload pressure, and mechanical shock, the DAQ-GP-PS485 also offers low temperature drift, high stability, and exceptional measurement accuracy. These characteristics make it an ideal pressure measurement instrument for industrial automation, process control, water treatment, energy management, hydraulic systems, and various Industrial IoT (IIoT) applications.

2 Working Principle****

The pressure sensor utilizes aWheatstone bridge diffused onto a silicon diaphragm. When pressure from the measured medium is applied to the sensing element, the resistance values of the bridge arms change due to the piezoresistive effect , generating a differential voltage signal.

This differential signal is then processed and amplified by a dedicated signal conditioning circuit, which converts it into a standard analog or digital output signal proportional to the corresponding pressure range.

The resulting output can be directly transmitted to PLCs, SCADA systems, RTUs, data acquisition devices, and Industrial IoT platforms for real-time pressure monitoring and control.

3**Service Concept**

Our company solemnly promises:

You buy not only the product, but also the meticulous and thoughtful technical support service ! ! ! ( =^_^= )

This product only needs ordinary workers to connect the power and install it on site! No debugging is required!

We provide free remote guidance, remote configuration and debugging services, and send data to the user’s designated cloud platform.

As an expert in industrial data collection, Shucai IoT provides free IoT solution consulting services!

4 Technical Specifications****

Parameter	Specification
Measured Medium	Liquids or gases compatible with wetted materials
Wetted Materials	Diaphragm: 316L Stainless Steel
	Process Connection: 304 Stainless Steel
	Seal: Nitrile Rubber (NBR)
Housing Material	304 Stainless Steel
Electrical Connection	Hirschmann Connector (Standard), Waterproof Cable Gland (Direct Cable), Aviation Connector
Pressure Range	-100 kPa to 4 kPa up to 100 MPa (Refer to Selection Guide)
Pressure Reference	Gauge Pressure (GP), Absolute Pressure (AP), Vacuum Pressure
Output Signal	4–20 mA (Standard, Power Supply: 8–30 VDC)
	0–10 V (Power Supply: 12–30 VDC)
	0–5 V, 1–5 V, 1–10 V, 0.5–4.5 V (Customized)
	RS485 (Standard Modbus RTU Protocol, Power Supply: 6–30 VDC)
Accuracy	±0.2% FS, ±0.5% FS (Available for ranges ≥ 4 kPa, customized)
Medium Temperature	-20°C to +70°C
Ambient Temperature	-20°C to +70°C
Ambient Humidity	0% to 95% RH (Non-condensing)
Temperature Compensation Range	-10°C to +70°C
Vibration Resistance	10 g (20 to 2000 Hz)
Overload Capacity	200% of Full Scale (FS)
Response Frequency	10 Hz to 1200 Hz
Long-Term Stability	±0.1% FS/year
Temperature Drift	±0.01% FS/°C (Within Compensation Range)
Protection Rating	IP65 / IP67

5 Product Dimensions****

6 Wiring Connection****

7 Precautions for Use****

1.Installation must be carried out only when the system is depressurized and the power supply is disconnected.

2. Do not use the transmitter to measure media that are incompatible with the wetted materials of the sensor.

3. Do not modify, disassemble, or alter the device in any way.

4. As this product is a low-voltage electronic device, ensure that both the pressure source and power supply are disconnected before wiring or maintenance to prevent accidents caused by media leakage or ejection.

5. For pressure ranges below 0.03 MPa , vertical installation is recommended (except for models specifically designed for gas measurement) to ensure optimal measurement accuracy.

6. When measuring high-temperature steam or gas media, ensure that the medium temperature does not exceed the transmitter’s specified operating temperature range. If necessary, install a cooling device or siphon tube to reduce the temperature at the sensing element.

7. During installation, use a wrench to tighten the transmitter at the hexagonal fitting located at the base of the process connection. Do not rotate the upper housing directly, as this may damage or disconnect the electrical wiring.

8. Verify that the power supply voltage complies with the transmitter’s specified requirements and that the maximum pressure of the pressure source does not exceed the transmitter’s rated pressure range.

9. The sensing element is a precision component. Users should not disassemble the sensor or touch the pressure diaphragm, as this may result in permanent damage and affect measurement performance.

Safety Notes****

· Read the operating instructions carefully before installation and use.

· Follow all applicable electrical and safety regulations.

· Protect the transmitter from excessive vibration, mechanical shock, and corrosive environments.

· Regularly inspect wiring, seals, and process connections to ensure reliable operation.

· Improper installation or operation may affect measurement accuracy and product lifespan.

FAQ – RS485 Modbus High Precision Pressure Transducer Sensor

1. What communication protocol does this pressure sensor support?

The sensor uses the standard Modbus RTU protocol over RS485 , making it compatible with most PLCs, HMIs, SCADA systems, industrial PCs, and IoT gateways.

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2. Can the sensor be connected directly to a PLC?

Yes. The sensor can be connected directly to PLCs from major brands such as Siemens, Schneider Electric, Mitsubishi, Delta, Omron, Allen-Bradley, and WAGO through the RS485 interface.

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3. What pressure ranges are available?

Multiple pressure ranges are available, including:

• -100kPa ~ 0kPa (Vacuum)

• 0 ~ 100kPa

• 0 ~ 1MPa

• 0 ~ 10MPa

• 0 ~ 60MPa

• 0 ~ 100MPa

Custom pressure ranges can also be provided upon request.

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4. What types of pressure can be measured?

The sensor supports:

• Gauge Pressure

• Absolute Pressure

• Vacuum Pressure

• Compound Pressure

• Sealed Gauge Pressure

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5. What is the measurement accuracy?

Standard accuracy is ±0.25% FS , with optional ±0.1% FS high-precision versions available for demanding industrial applications.

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6. What media can the sensor measure?

Suitable media include:

• Water

• Compressed Air

• Hydraulic Oil

• Diesel Fuel

• Refrigerants

• Non-corrosive Liquids

• Non-corrosive Gases

For corrosive media, a 316L stainless steel diaphragm version is recommended.

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7. Can the sensor be used outdoors?

Yes. With an IP65 or IP67 protection rating, the sensor is suitable for outdoor installations, pump stations, water treatment facilities, and industrial environments.

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8. What is the maximum RS485 communication distance?

Under proper wiring conditions, RS485 communication can reach up to 1200 meters (3937 ft).

For longer distances, the sensor can be connected to:

• 4G IoT Gateways

• Ethernet Gateways

• LoRaWAN Gateways

• NB-IoT Data Loggers

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9. Can multiple pressure sensors share the same RS485 network?

Yes. Each sensor can be assigned a unique Modbus address, allowing multiple devices to communicate on the same RS485 bus.

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10. Does the sensor support remote monitoring?

Yes. By connecting to an Industrial IoT Gateway, pressure data can be transmitted to:

• Cloud Platforms

• SCADA Systems

• Mobile Applications

• Web Dashboards

• Remote Monitoring Centers

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11. What power supply is required?

Typical supply voltage options include:

• DC 12V

• DC 24V

• DC 9~36V Wide Voltage Input (Optional)

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12. What thread connections are available?

Common pressure connections include:

• G1/4

• G1/2

• NPT1/4

• NPT1/2

• M20×1.5

Custom process connections are also available.

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13. Is customization available?

Yes. OEM and ODM services include:

• Custom Pressure Ranges

• Private Label Branding

• Customized Modbus Registers

• Special Connectors

• Custom Cable Lengths

• Custom Housing Materials

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14. Can this pressure sensor work with SCADA systems?

Yes. The Modbus RTU protocol allows seamless integration with popular SCADA platforms, including:

• Ignition

• Wonderware

• WinCC

• KingView

• iFIX

• VTScada

• Citect SCADA

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15. What industries commonly use this sensor?

Water & Wastewater

• Pump Stations

• Water Treatment Plants

• Water Distribution Networks

Industrial Automation

• Factory Equipment

• Process Control Systems

• Smart Manufacturing

Energy & Utilities

• District Heating Systems

• Power Plants

• Renewable Energy Projects

HVAC

• Chilled Water Systems

• Boiler Monitoring

• Air Handling Units

Oil & Gas

• Pipeline Monitoring

• Compressor Stations

• Storage Tank Systems

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16. Can the sensor be integrated into Industrial IoT projects?

Absolutely. The sensor is widely used in:

• Industrial IoT (IIoT)

• Smart Factory Projects

• Predictive Maintenance Systems

• Energy Monitoring Systems

• Remote Equipment Monitoring

• Digital Transformation Projects

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17. How do I read data from the sensor?

Pressure values can be read using:

• PLC Modbus Polling

• SCADA Software

• HMI Displays

• RS485-to-USB Converters

• Industrial IoT Gateways

A complete Modbus Register Map and Communication Protocol Manual is provided upon request.

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18. Why choose an RS485 Modbus pressure sensor instead of a 4-20mA pressure transmitter?

RS485 Modbus Advantages:

✔ Higher measurement accuracy
✔ Digital transmission without signal drift
✔ Long-distance communication up to 1200m
✔ Multiple sensors on one communication bus
✔ Easier integration with PLC and IoT systems
✔ Reduced wiring costs for large installations

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19. What is the expected service life?

Under normal operating conditions, the sensor typically provides more than 5 years of stable operation , with high long-term reliability and low maintenance requirements.

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20. Do you provide OEM/ODM and bulk order support?

Yes. DAQ-IOT supports:

✔ OEM Manufacturing
✔ Distributor Partnerships
✔ Project-Based Customization
✔ Industrial IoT Solution Integration
✔ Global Technical Support
✔ Sample Evaluation Units