7 in 1 Soil sensor NPK value not change

[nop18]

Hello guys, can you help me ? i have problem on my NPK sensor. My sensor already can get 4 value from sensor like pH, Temprature, EC, Humidity, but N P K value is not working. This is my code i got from tutorials on youtube.

#include <SoftwareSerial.h>

SoftwareSerial mySerial(4, 3);  // RX, TX

void setup() {
  Serial.begin(9600);
  mySerial.begin(4800);
}

void loop() {
  byte queryData[] = {0x01, 0x03, 0x00, 0x00, 0x00, 0x07, 0x08, 0x04};
  byte receivedData[19];

  mySerial.write(queryData, sizeof(queryData));  
  delay(1000);  
  mySerial.flush();

  if (mySerial.available() >= sizeof(receivedData)) {  
    mySerial.readBytes(receivedData, sizeof(receivedData));  

    
    unsigned int soilHumidity = (receivedData[3] << 8) | receivedData[4];
    unsigned int soilTemperature = (receivedData[5] << 8) | receivedData[6];
    unsigned int soilConductivity = (receivedData[7] << 8) | receivedData[8];
    unsigned int soilPH = (receivedData[9] << 8) | receivedData[10];
    unsigned int nitrogen = (receivedData[11] << 8) | receivedData[12];
    unsigned int phosphorus = (receivedData[13] << 8) | receivedData[14];
    unsigned int potassium = (receivedData[15] << 8) | receivedData[16];

    
    float kelembapanTanah = (float)soilHumidity / 20.0;
    float SuhuTanah = 1.0175*(soilTemperature / 10.0) - 1.1524;


    Serial.print("Humidity : ");
    Serial.println(soilHumidity);
    Serial.print("Temp : ");
    Serial.println(SuhuTanah);
    Serial.print("EC : ");
    Serial.println(soilConductivity);
    Serial.print("pH : ");
    Serial.println((float)soilPH / 10.0);
    Serial.print("N : ");
    Serial.println(nitrogen);
    Serial.print("P : ");
    Serial.println(phosphorus);
    Serial.print("K : ");
    Serial.println(potassium);  
    // delay(30000);
  }
}

And i use this RS485 :

instead of using the default like this, because i always get 255 value.

previously my npk value always get 0, and now stuck on 32 for n, 88 for p and 104 for k after my friend use Coolterm software. i dont know why.

this is my sensor :

[rsmls]

@nop18

my NPK sensor

AFAIK there's no reliable way to measure NPK with a simple sensor. It requires chemical lab analysis. I wouldn't even bother trying to get this to work; it's a waste of time.

[jremington]

@nop18

but N P K value is not working.

The sensor does not measure N, P or K values. It is not entirely clear what those things do, but you make have a defective fake that cannot even make up numbers.

[xfpd]

Verify the sensor, transceiver and Arduino share the ground wire.

[qubits-us]

Hi @nop18 ,

Welcome to the forum..
The checksum looks backwards..

@nop18

{0x01, 0x03, 0x00, 0x00, 0x00, 0x07, 0x08, 0x04};

should be..

{0x01, 0x03, 0x00, 0x00, 0x00, 0x07, 0x04, 0x08}

good luck.. ~q

[nop18]

Sry guys, just back from college.
ah really ? i think it will work. But i find some documentation about NPK sensor and its working @@ .

[nop18]

this is my wiring.

i try to find this app but cant find it.

So i try using Qmodmaster and CoolTerm for checking the address.

[nop18]

thanks
i try this but my sensor not respond.

[qubits-us]

Could be the power source if you are indeed powering this sensor using a 9v battery..
Could also be on the wrong address..
Check this sketch out..
USE_CAST is defined as true, it will use the second set of data with address 255..
Address 255 is the broadcast address, all sensors should respond and change the 255 with their currently set address..
As the address and baud rate can be changed..
Try address 255 and also different bauds..
double check wiring..

good luck.. ~q

[nop18]

I've tried it on 9v, 12v, and 24v but still same. Im using this

and this is my sensor address

i use 0000 until 0006 address.

I use your code and this is my output

Is it like this ?
but the value still stuck at 32, 88 and 104.

[rsmls]

@nop18

but the value still stuck at 32, 88 and 104.

So? As I said earlier, there's no way a sensor like that can specifically measure N, P or K. It'll produce numbers, but they won't mean anything.

[qubits-us]

Yes, it looks like you are getting proper response back from the sensor..
No idea how these sensors work or if they in fact do..

good luck.. ~q