SKU: TH2223
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RS485 Photosynthetically Active Radiation (PAR) Sensor is designed to measure plant-useful light in the 400-700nm spectral range. It reports PAR values in µmol/m²·s, making it suitable for crop monitoring, greenhouse automation, plant research, and other light-measurement tasks where photosynthetic activity matters more than general illuminance.
The sensor uses an RS485 interface with Modbus-RTU communication, so it can be integrated into industrial controllers, data loggers, PLC-based systems, and microcontroller projects using an RS485-to-UART converter. A wide DC 5-30V supply range and low working current of less than 10mA make system integration straightforward.
Its IP67 protection rating helps it handle demanding field installations in agriculture, environmental monitoring, and outdoor test setups. Typical applications include agricultural light monitoring, photovoltaic radiation studies, and ecological or environmental data collection.
Technical details for the RS485 PAR sensor.
| Brand | DFRobot |
|---|---|
| Model | SEN0641 |
| Power Supply | DC 5-30V |
| Working Current | <10mA |
| Output Interface | RS485 |
| Protocol | Modbus-RTU |
| Wavelength Range | 400-700nm |
| Measurement Range | 0-2500 µmol/m²·s |
| Resolution | 1 µmol/m²·s |
| Accuracy | ±5% (1000 µmol/m²·s @ 550nm, 60%RH, 25°C) |
| Response Time | 10 µs |
| Non-Linearity | <±1% |
| Annual Stability | ≤±2% |
| Cosine Response | ≤±10% |
| Operating Temperature | -25°C to +60°C |
| Protection Rating | IP67 |
| Sensor Cable Length | 20cm |
| Adapter Cable Length | 70cm |
The sensor communicates over RS485 using Modbus-RTU with 8 data bits, no parity, 1 stop bit, and CRC error checking. Supported baud rates are 2400, 4800, and 9600 bit/s, with a factory default device address of 0x01 and default baud rate of 4800 bit/s.
Useful registers include 0000H for the current PAR value, 0052H for deviation value, 07D0H for device address, and 07D1H for baud rate configuration.
Wire mapping for power and RS485 communication.
| Wire | Name | Function |
|---|---|---|
| Brown | VCC | Power input positive, DC 5-30V |
| Black | GND | Power ground |
| Yellow | 485-A | RS485 data line A |
| Blue | 485-B | RS485 data line B |
Do not disassemble the sensor, as it is a precision device. If the reading is zero, check that a valid light source is present and that the protective cover has been removed before use. Also verify RS485 A/B wiring polarity and confirm the supply voltage is within the marked range.
Please note: one source lists the measurement range as 0-2500 µmol/m²·s, while the guide specification mentions 0-4000 µmol/m²·s. This listing follows the primary supplier brief value of 0-2500 µmol/m²·s.
It measures photosynthetically active radiation in the 400-700nm band, which is the light range used by plants for photosynthesis. Readings are reported in µmol/m²·s.
The sensor operates on DC 5-30V and has a working current of less than 10mA. The brown wire is VCC and the black wire is GND.
It uses RS485 with Modbus-RTU protocol. Communication settings support 8 data bits, no parity, 1 stop bit, CRC error checking, and configurable baud rates of 2400, 4800, or 9600 bit/s, with 4800 bit/s as default.
The pinout is: brown = VCC, black = GND, yellow = 485-A, and blue = 485-B. For communication, connect both RS485 A/B lines correctly and provide a DC 5-30V supply.
One source lists the measurement range as 0-2500 µmol/m²·s, while the linked guide specification lists 0-4000 µmol/m²·s. If your application depends on the upper limit, it is best to verify the exact range for this listing before purchase.
According to the reference material, common causes include no light source, the protective cover not being removed, reversed or disconnected RS485 A/B wiring, or an incorrect power supply. The factory default Modbus address is 0x01, so communication settings should also match the sensor configuration.
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