Hello! I'm facing a problem. When I use the same code that how2electronics has provided for the NPK sensor, the Max485 to TTL converter / Modbus we're using simply returns FFFFFF, and thus just constantly outputs 255, 255, 255 for the values. Any idea on why this might be happening?
source code :
#include <SoftwareSerial.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define OLED_RESET -1 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
#define RE 8
#define DE 7
//const byte code[]= {0x01, 0x03, 0x00, 0x1e, 0x00, 0x03, 0x65, 0xCD};
const byte nitro[] = {0x01,0x03, 0x00, 0x1e, 0x00, 0x01, 0xe4, 0x0c};
const byte phos[] = {0x01,0x03, 0x00, 0x1f, 0x00, 0x01, 0xb5, 0xcc};
const byte pota[] = {0x01,0x03, 0x00, 0x20, 0x00, 0x01, 0x85, 0xc0};
byte values[11];
SoftwareSerial mod(2,3);
void setup() {
Serial.begin(9600);
mod.begin(9600);
pinMode(RE, OUTPUT);
pinMode(DE, OUTPUT);
display.begin(SSD1306_SWITCHCAPVCC, 0x3C); //initialize with the I2C addr 0x3C (128x64)
delay(500);
display.clearDisplay();
display.setCursor(25, 15);
display.setTextSize(1);
display.setTextColor(WHITE);
display.println(" NPK Sensor");
display.setCursor(25, 35);
display.setTextSize(1);
display.print("Initializing");
display.display();
delay(3000);
}
void loop() {
byte val1,val2,val3;
val1 = nitrogen();
delay(250);
val2 = phosphorous();
delay(250);
val3 = potassium();
delay(250);
Serial.print("Nitrogen: ");
Serial.print(val1);
Serial.println(" mg/kg");
Serial.print("Phosphorous: ");
Serial.print(val2);
Serial.println(" mg/kg");
Serial.print("Potassium: ");
Serial.print(val3);
Serial.println(" mg/kg");
delay(2000);
display.clearDisplay();
display.setTextSize(2);
display.setCursor(0, 5);
display.print("N: ");
display.print(val1);
display.setTextSize(1);
display.print(" mg/kg");
display.setTextSize(2);
display.setCursor(0, 25);
display.print("P: ");
display.print(val2);
display.setTextSize(1);
display.print(" mg/kg");
display.setTextSize(2);
display.setCursor(0, 45);
display.print("K: ");
display.print(val3);
display.setTextSize(1);
display.print(" mg/kg");
display.display();
}
byte nitrogen(){
digitalWrite(DE,HIGH);
digitalWrite(RE,HIGH);
delay(10);
if(mod.write(nitro,sizeof(nitro))==8){
digitalWrite(DE,LOW);
digitalWrite(RE,LOW);
for(byte i=0;i<7;i++){
//Serial.print(mod.read(),HEX);
values[i] = mod.read();
Serial.print(values[i],HEX);
}
Serial.println();
}
return values[4];
}
byte phosphorous(){
digitalWrite(DE,HIGH);
digitalWrite(RE,HIGH);
delay(10);
if(mod.write(phos,sizeof(phos))==8){
digitalWrite(DE,LOW);
digitalWrite(RE,LOW);
for(byte i=0;i<7;i++){
//Serial.print(mod.read(),HEX);
values[i] = mod.read();
Serial.print(values[i],HEX);
}
Serial.println();
}
return values[4];
}
byte potassium(){
digitalWrite(DE,HIGH);
digitalWrite(RE,HIGH);
delay(10);
if(mod.write(pota,sizeof(pota))==8){
digitalWrite(DE,LOW);
digitalWrite(RE,LOW);
for(byte i=0;i<7;i++){
//Serial.print(mod.read(),HEX);
values[i] = mod.read();
Serial.print(values[i],HEX);
}
Serial.println();
}
return values[4];
}
