RS485 Photosynthetically Active Radiation (PAR) Sensor (400-700nm) - แท้ DFRobot

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สรุปคุณสมบัติ
เซ็นเซอร์ PAR (หรือ Photosynthetically Active Radiation) แบบ RS485 วัดแสงที่พืชใช้จริงช่วง 400–700 nm พร้อม cosine correction ให้ค่าถูกต้องทุกมุมและเอาต์พุตเป็นสัดส่วนกับความเข้มแสง รองรับ RS485 Modbus-RTU และไฟ 5–30V เชื่อมต่อ Arduino PLC หรือ LoRa ได้ทันที โครงสร้างอะลูมิเนียมมาตรฐาน IP67 พร้อมฝาครอบกันฝุ่น ทนแดดฝนสำหรับงานกลางแจ้งระยะยาว เหมาะสำหรับเรือนกระจก เกษตรอัจฉริยะ และสถานีตรวจอากาศที่ต้องการข้อมูล PAR ที่แม่นยำและเชื่อถือได้

Introduction

The RS485 Photosynthetically Active Radiation (PAR) Sensor is designed to measure the amount of light that plants can utilize during photosynthesis. It operates within the spectral range of 400-700nm, which corresponds to the light needed for plant growth. The sensor converts sunlight into a voltage signal that is directly proportional to the intensity of the incident radiation, with sensitivity that follows the cosine of the light's angle of incidence. This high-precision sensor is equipped with a specially treated dust cover to prevent environmental interference, ensuring reliable measurements. The sensor supports Modbus-RTU communication via RS485 and operates with a wide DC voltage range of 5-30V, making it compatible with various platforms like Arduino.

Wide Voltage Range and Easy Integration

The sensor operates with a DC power supply from 5-30V, offering flexibility for integration into diverse systems. It supports RS485 communication using the standard Modbus-RTU protocol, making it simple to interface with Arduino and similar platforms for data collection.

High Precision and Reliability

The sensor features high-precision photoelectric elements with wide spectrum absorption, ensuring accurate measurements of photosynthetically active radiation (PAR) in the 400-700nm range. Additionally, the sensor's cosine corrector guarantees an accurate response to varying light angles, essential for precise environmental monitoring.

Durable and Weather-Resistant

Constructed with a metal aluminum shell and rated IP67 for protection against dust and water, the sensor is highly durable and suitable for use in harsh outdoor environments. The specially treated dust cover ensures long-term stability by minimizing the effects of environmental contamination.

RS485 PAR sensor measures photosynthetically active radiation (PAR) for plant photosynthesis.

Applications

• Agricultural Monitoring: Measuring light intensity for optimizing crop growth and assessing plant health.
• Photovoltaic Systems: Monitoring solar radiation for efficient solar energy generation.
• Environmental and Ecological Research: Collecting data on radiation levels to support environmental studies and ecological conservation efforts.

Specification

• Power Supply: DC 5-30V
• Working Current: ＜10mA
• Output Mode: RS485
• Measurement Range: 0-2500 µmol/m²·s
• Wavelength Range: 400-700nm
• Accuracy: ±5% (1000 µmol/m²·s @ 550nm, 60%RH, 25°C)
• Resolution: 1 µmol/m²·s
• Response Time: 10 µs
• Non-Linearity: ＜±1%
• Annual Stability: ≤±2%
• Cosine Response: ≤±10%
• Operating Temperature: -25°C to +60°C
• Protection Level: IP67
• Sensor Cable Length: 20cm
• Adapter Cable Length: 70cm

Documents

• Product wiki
• Dimensional Drawing
• Communication Protocol
• Tutorial
• FAQ

Shipping List

• RS485 PAR Sensor x1

• Adapter Cable x1

• Screw Package x1

Tutorial

Requirements

• Hardware
  • DFRduino UNO R3 (or similar) x 1
  • Gravity: Active Isolated RS485 to UART Signal Adapter Module x1
  • RS485 Photosynthetically Active Radiation(PAR)Sensor x1

• Software
  • Arduino IDE

Connection Diagram

If the power of the RS485 device is small and the required current is less than 12V-160mA, the RS485 to UART signal conversion module does not require a 12V external power supply, making wiring more convenient.

Sample Code

#include <SoftwareSerial.h>
SoftwareSerial mySerial(2,3);
uint8_t Com[8] = { 0x01, 0x03, 0x00, 0x00, 0x00, 0x01, 0x84, 0x0A };
int PAR;
void setup() {
Serial.begin(9600);
mySerial.begin(4800);
}
void loop() {
readPAR();
Serial.print("PAR = ");
Serial.print(PAR);
Serial.println(" umol/m²·s ");
delay(1000);
}

void readPAR(void) {
uint8_t Data[10] = { 0 };
uint8_t ch = 0;
bool flag = 1;
while (flag) {
delay(100);
mySerial.write(Com, 8);
delay(100);
if (readN(&ch, 1) == 1) {
if (ch == 0x01) {
Data[0] = ch;
if (readN(&ch, 1) == 1) {
if (ch == 0x03) {
Data[1] = ch;
if (readN(&ch, 1) == 1) {
if (ch == 0x02) {
Data[2] = ch;
if (readN(&Data[3], 4) == 4) {
if (CRC16_2(Data, 5) == (Data[5] * 256 + Data[6])) {
PAR = Data[3] * 256 + Data[4];
flag = 0;
}
}
}
}
}
}
}
}
mySerial.flush();
}
}

uint8_t readN(uint8_t *buf, size_t len) {
size_t offset = 0, left = len;
int16_t Tineout = 500;
uint8_t *buffer = buf;
long curr = millis();
while (left) {
if (mySerial.available()) {
buffer[offset] = mySerial.read();
offset++;
left--;
}
if (millis() - curr > Tineout) {
break;
}
}
return offset;
}

unsigned int CRC16_2(unsigned char *buf, int len) {
unsigned int crc = 0xFFFF;
for (int pos = 0; pos < len; pos++) {
crc ^= (unsigned int)buf[pos];
for (int i = 8; i != 0; i--) {
if ((crc & 0x0001) != 0) {
crc >>= 1;
crc ^= 0xA001;
} else {
crc >>= 1;
}
}
}

crc = ((crc & 0x00ff) << 8) | ((crc & 0xff00) >> 8);
return crc;
}

Expected Results

Print the collected photosynthetically active radiation value, which cannot be collected by ordinary indoor light sources.

FAQ

Possible reasons for no output or output errors:

1. The sensor is a precision device. Please do not disassemble it by yourself when using it to avoid damage to the product.
2. If the reading value is 0, check whether there is a light source and whether the product protective cover is removed.
3. The 485 bus is disconnected, or the A and B lines are connected in reverse.
4. Check whether the power supply meets the marking.