CPE241 Week 13

Modbus

Modbus Communication Overview:

ModbusMaster Library: Used for implementing Modbus RTU communication in Arduino. SoftwareSerial: Configures UART communication (pins 14 and 12) for Modbus RTU via a MAX485 transceiver. MAX485 Transceiver: Used for converting TTL (UART) signals to RS485 for Modbus communication. RE (Receiver Enable) and DE (Driver Enable) pins control data flow direction (receive/send).

RS485 + XY-MD02

#include <SoftwareSerial.h>
#include <ModbusMaster.h>

SoftwareSerial md02Serial(14, 12); // RX, TX

#define MAX485_DE 4
#define MAX485_RE_NEG 5

ModbusMaster node;

void preTransmission()
{
  digitalWrite(MAX485_RE_NEG, 1);
  digitalWrite(MAX485_DE, 1);
}

void postTransmission()
{
  digitalWrite(MAX485_RE_NEG, 0);
  digitalWrite(MAX485_DE, 0);
}

void setup()
{
  Serial.begin(115200);
  md02Serial.begin(9600);

  pinMode(MAX485_RE_NEG, OUTPUT);
  pinMode(MAX485_DE, OUTPUT);

  digitalWrite(MAX485_RE_NEG, 0);
  digitalWrite(MAX485_DE, 0);

  node.begin(1, md02Serial);
  node.preTransmission(preTransmission);
  node.postTransmission(postTransmission);
}

void loop()
{
  uint8_t result;
  double t;
  double h;

  Serial.println("XY-MD02 data");

  result = node.readInputRegisters(1, 2);

  if (result == node.ku8MBSuccess)
  {
    t = node.getResponseBuffer(0) / 10.0f;
    h = node.getResponseBuffer(1) / 10.0f;

    Serial.print("Temp: ");
    Serial.println(t);
    Serial.print("Humid: ");
    Serial.println(h);
    Serial.println();
  }

  delay(1000);
}

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ADD data To firebase

#include "FirebaseESP8266.h"
#include <ESP8266WiFi.h>

#include <SoftwareSerial.h>
#include <ModbusMaster.h>

#define FIREBASE_HOST "YOUR_FIREBASE_HOST"
#define FIREBASE_AUTH "YOUR_FIREBASE_AUTH"
#define WIFI_SSID "YOUR_WIFI_SSID"
#define WIFI_PASSWORD "YOUR_WIFI_PASSWORD"

SoftwareSerial md02Serial(14, 12); // RX, TX

#define MAX485_DE 5
#define MAX485_RE_NEG 4

ModbusMaster node;
FirebaseData firebaseData;
FirebaseJson json;
String path = "MD02";

void preTransmission()
{
  digitalWrite(MAX485_RE_NEG, 1);
  digitalWrite(MAX485_DE, 1);
}

void postTransmission()
{
  digitalWrite(MAX485_RE_NEG, 0);
  digitalWrite(MAX485_DE, 0);
}

void setup()
{
  Serial.begin(115200);
  md02Serial.begin(9600);
  pinMode(MAX485_RE_NEG, OUTPUT);
  pinMode(MAX485_DE, OUTPUT);

  digitalWrite(MAX485_RE_NEG, 0);
  digitalWrite(MAX485_DE, 0);

  node.begin(1, md02Serial);
  node.preTransmission(preTransmission);
  node.postTransmission(postTransmission);

  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  Serial.print("Connecting to Wi-Fi");
  while (WiFi.status() != WL_CONNECTED)
  {
    Serial.print(".");
    delay(300);
  }
  Serial.println();
  Serial.print("Connected with IP: ");
  Serial.println(WiFi.localIP());

  Serial.println();
  Firebase.begin(FIREBASE_HOST, FIREBASE_AUTH);
  Firebase.reconnectWiFi(true);
  Firebase.setReadTimeout(firebaseData, 1000 * 60);
  Firebase.setwriteSizeLimit(firebaseData, "tiny");
}

void loop()
{
  uint8_t result;
  double t;
  double h;

  Serial.println("XY-MD02 data");
  result = node.readInputRegisters(1, 2);

  if (result == node.ku8MBSuccess)
  {
    t = node.getResponseBuffer(0) / 10.0f;
    h = node.getResponseBuffer(1) / 10.0f;

    Serial.print("Temp: ");
    Serial.println(t);
    Serial.print("Humid: ");
    Serial.println(h);
    Serial.println();
  }

  json.add("temp", t);
  json.add("humid", h);
  Firebase.set(firebaseData, path, json);

  delay(1000);
}

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