This is the temporary installation of my Anemometer & Wind Vane to test via RS-485 into a couple of ESP-32's. The outside temp is currently -30C so I'm not in any hurry to mount these up higher where they will be unobstructed!
Here is the pic of the 12V supply feeding a buck converter down to 5VDC to feed both ESP32's, one for the Anemometer and one for the Wind Vane. Buck converter in the centre under the white CAT5 cable that feeds 12VDC power to the devices and brings back 2 wires each RS485 to the RS485>TTL converters (top & bottom of photo). You can see one of the ESP32's with the green tape showing 00 on it.
You are supposed to be able to change the addresses on the devices (they all default to 1) so that they can share the same RS485 buss, but the documentation is sparse on these units and rather than take the chance that I 'brick' them, I'm leaving the addresses alone. Which means that I now have 3 devices (Anemometer, Wind Vane & Temperature/Humidity Sensor that are all RS485.
After receiving my Raspberry Pi Pico 2W's I started reading the documentation and found that the PIO function allows for additional UART's (it comes with 2), so I wrote a sketch to talk to 3 RS485>TTL boards from the 2 UARTs and 1 SoftwareSerial PIO-based UART
Here is a line diagram of the original circuit before I added the Pico, third TTL>RS485 board & Temp/Humidity Sensor
/*
* TempHumidRS485_3.ino
* Robin Greig
* 2025.02.17
*
* Reads the Temp & Humidity of RS485 device and prints it to Serial Monitor
*
* Using both UARTS and PIO-based UART to read 3 RS485 > TTL inputs
* mySerial1 = Rx / Pin 2 / GPIO 1 & Tx / Pin 1 / GPIO 0
* mySerial2 = Rx / Pin 7 / GPIO 5 & Tx / Pin 6 / GPIO 4
* mySerial3 = SerialPIO = Tx / Pin 11 / GPIO 8 & Rx / Pin 12 / GPIO 9
*
* Addint mqtt connectivity
*
* Based on the ModbusMaster example below
*/
#include <ModbusMaster.h> //https://github.com/4-20ma/ModbusMaster
#include <SoftwareSerial.h>
#include <WiFi.h>
#include <PubSubClient.h>
#include <string.h>
// Create a SoftwareSerial object to communicate with the MAX485 module
SoftwareSerial mySerial1(1, 0); // Rx-Pin 2-GPIO 1 & Tx-Pin 1-GPIO 0
SoftwareSerial mySerial2(5, 4); // Rx-Pin 2-GPIO 1 & Tx-Pin 1-GPIO 0
SerialPIO mySerial3(8, 9); // Tx-GPIO 8-Pin 11 & Rx-GPIO 12-Pin 10
//for SoftwareSerial PIO-based UART
// Create a ModbusMaster object
ModbusMaster node1;
ModbusMaster node2;
ModbusMaster node3;
// WiFi
const char *ssid = "Calalta02"; // Enter your WiFi name
const char *password = "Micr0s0ft2018"; // Enter WiFi password
// MQTT Broker
const char *mqtt_broker = "192.168.200.143";
const char *topic1 = "pico2w/00/temp1";
const char *topic2 = "pico2w/00/humid1";
const char *topic3 = "pico2w/00/temp2";
const char *topic4 = "pico2w/00/humid2";
const char *topic5 = "pico2w/00/temp3";
const char *topic6 = "pico2w/00/humid3";
const int mqtt_port = 1883;
WiFiClient espClient;
PubSubClient client(espClient);
float humidity1;
char humidChar1 [6];
float humidity2;
char humidChar2 [6];
float humidity3;
char humidChar3 [6];
float temperature1;
char tempChar1 [6];
float temperature2;
char tempChar2 [6];
float temperature3;
char tempChar3 [6];
void setup() {
// Initialize serial communication for debugging
Serial.begin(115200);
// Initialize SoftwareSerial for Modbus communication
mySerial1.begin(9600);
mySerial2.begin(9600);
mySerial3.begin(9600);
// Initialize Modbus communication with the Modbus slave ID 1
node1.begin(1, mySerial1);
node2.begin(1, mySerial2);
node3.begin(1, mySerial3);
WiFi.begin(ssid, password); // connecting to the WiFi network
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.println("Connecting to WiFi..");
}
Serial.println("Connected to the WiFi network");
//connecting to a mqtt broker
client.setServer(mqtt_broker, mqtt_port);
while (!client.connected()) {
String client_id = "pico2w-00 > ";
client_id += String(WiFi.macAddress());
Serial.printf("The client %s is connecting to the mqtt broker\n", client_id.c_str());
// if (client.connect(client_id.c_str(), mqtt_username, mqtt_password)) {
if (client.connect(client_id.c_str())) {
Serial.println("Mqtt broker connected");
} else {
Serial.print("failed with state ");
Serial.print(client.state());
delay(1000);
}
// Allow some time for initialization
delay(500);
}
}
void loop() {
uint8_t result1; // Variable to store the result of Modbus operations
uint16_t data1[2]; // Array to store the data read from the Modbus slave
uint8_t result2; // Variable to store the result of Modbus operations
uint16_t data2[2]; // Array to store the data read from the Modbus slave
uint8_t result3; // Variable to store the result of Modbus operations
uint16_t data3[2]; // Array to store the data read from the Modbus slave
// Read 2 holding registers for node1 starting at address 0x0000
// This function sends a Modbus request to the slave to read the registers
// result1 = node1.readHoldingRegisters(0x0000, 2);
result1 = node1.readHoldingRegisters(0x0000, 2);
// If the read is successful, process the data
if (result1 == node1.ku8MBSuccess) {
// Get the response data from the response buffer
data1[0] = node1.getResponseBuffer(0x00); // Humidity
data1[1] = node1.getResponseBuffer(0x01); // Temperature
// Calculate actual humidity and temperature values
humidity1 = data1[0] / 10.0; // Humidity is scaled by 10
temperature1 = data1[1] / 10.0; // Temperature is scaled by 10
// Print the values to the Serial Monitor
Serial.print("Humidity1: ");
Serial.print(humidity1);
Serial.println(" %RH");
Serial.print("Temperature1: ");
Serial.print(temperature1);
Serial.println(" °C");
Serial.println();
} else {
// Print an error message if the read fails
Serial.print("Modbus read failed: ");
Serial.println(result1, HEX); // Print the error code in hexadecimal format
Serial.println();
}
delay(200);
// Read 2 holding registers for node2 starting at address 0x0000
// This function sends a Modbus request to the slave to read the registers
result2 = node2.readHoldingRegisters(0x0000, 2);
// If the read is successful, process the data
if (result2 == node2.ku8MBSuccess) {
// Get the response data from the response buffer
data2[0] = node2.getResponseBuffer(0x00); // Humidity
data2[1] = node2.getResponseBuffer(0x01); // Temperature
// Calculate actual humidity and temperature values
humidity2 = data2[0] / 10.0; // Humidity is scaled by 10
temperature2 = data2[1] / 10.0; // Temperature is scaled by 10
// Print the values to the Serial Monitor
Serial.print("Humidity2: ");
Serial.print(humidity2);
Serial.println(" %RH");
Serial.print("Temperature2: ");
Serial.print(temperature2);
Serial.println(" °C");
Serial.println();
} else {
// Print an error message if the read fails
Serial.print("Modbus read failed: ");
Serial.println(result2, HEX); // Print the error code in hexadecimal format
Serial.println();
}
delay(200);
// Read 2 holding registers for node3 starting at address 0x0000
// This function sends a Modbus request to the slave to read the registers
result3 = node3.readHoldingRegisters(0x0000, 2);
// If the read is successful, process the data
if (result3 == node3.ku8MBSuccess) {
// Get the response data from the response buffer
data3[0] = node3.getResponseBuffer(0x00); // Humidity
data3[1] = node3.getResponseBuffer(0x01); // Temperature
// Calculate actual humidity and temperature values
humidity3 = data3[0] / 10.0; // Humidity is scaled by 10
temperature3 = data3[1] / 10.0; // Temperature is scaled by 10
// Print the values to the Serial Monitor
Serial.print("Humidity3: ");
Serial.print(humidity3);
Serial.println(" %RH");
Serial.print("Temperature3: ");
Serial.print(temperature3);
Serial.println(" °C");
Serial.println();
} else {
// Print an error message if the read fails
Serial.print("Modbus read failed: ");
Serial.println(result3, HEX); // Print the error code in hexadecimal format
Serial.println();
}
client.loop();
//client.publish(topic, temperatureTest ); //publish temp
sprintf(tempChar1,"%.2f", temperature1);
Serial.print("tempChar1 = ");
Serial.println(tempChar1);
client.publish(topic1, tempChar1); //publish temp
sprintf(humidChar1,"%.2f",humidity1);
Serial.print("humidChar1 = ");
Serial.println(humidChar1);
client.publish(topic2, humidChar1);
sprintf(tempChar2,"%.2f", temperature2);
Serial.print("tempChar2 = ");
Serial.println(tempChar2);
client.publish(topic3, tempChar2); //publish temp
sprintf(humidChar2,"%.2f",humidity2);
Serial.print("humidChar2 = ");
Serial.println(humidChar2);
client.publish(topic4, humidChar2);
sprintf(tempChar3,"%.2f", temperature3);
Serial.print("tempChar3 = ");
Serial.println(tempChar3);
client.publish(topic5, tempChar3); //publish temp
sprintf(humidChar3,"%.2f",humidity3);
Serial.print("humidChar3 = ");
Serial.println(humidChar3);
client.publish(topic6, humidChar3);
// Wait for 2 seconds before the next read
delay(2000);
}
