RS485 with NodeMCU, ESP8266, ESP32, Arduino | RS485 Protocol | Implementation | Urdu | Hindi 

Dear you need to use write single/multiple register function to write data in holding registers. Please check sample code for Library which you are using.

So Sir can you tell me by which library I do this

Or In which library sample code is given

You can follow this video so you can understand. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-kFeTM5xicU8.html

Sir by this tutorial I does not understand anything. Please make seperate tutorial on it or give me another option to do this work

Hi Parveen, Yes, we can read and write if your pid controller support modbus protocol and for that you need read manual of modbus communication of your pid controller.

What are you doing in your code?

@@JPLearning i have 2 arduino and i intend for communicate via RS485 . i use software serial in arduino connect to rs485

@@iklasadichandra3003 tell me your connections and share code with me.

@@JPLearning can i send by email ?

@@iklasadichandra3003 sure

What is the issue you are facing?

I can't receive transmitted data from ESP32 master@@JPLearning

Why and what is the issue ? Share your code so I can check the issue

code master #include #define TEMPERATURE_REGISTER 0x00 // Địa chỉ register cho nhiệt độ #define Slave_ID 0 ModbusMaster node; void setup() { Serial.begin(9600); node.begin(0,Serial); } void loop() { int temperature = random(0, 100); // Giả lập nhiệt độ node.writeSingleRegister(TEMPERATURE_REGISTER, temperature); // Gửi dữ liệu nhiệt độ Serial.println("transmission temperature:"); Serial.println(temperature); delay(1000); } code slave #include #define TEMPERATURE_REGISTER 0x00 // adresse register temperature #define Slave_ID 1 ModbusMaster node; void setup() { Serial.begin(9600); node.begin(1,Serial); } void loop() { int temperature; int a; uint8_t vfdonoff= node.readHoldingRegisters(TEMPERATURE_REGISTER, 1); delay(25); // nếu đọc trạng thái thành công if(vfdonoff == node.ku8MBSuccess) { a = node.getResponseBuffer(vfdonoff); Serial.println("data temperature"); Serial.print(a); } else{ Serial.print("ERROL"); Serial.println(a); } delay(1000); } I use RS485 version 2 TxRx circuit but cannot transmit data. Please help me thank you @@JPLearning

@@JPLearning I cannot read the data received from the transmitting master and I use the RS485 V2 TxRx version. Please help me thank you Code master #include #define TEMPERATURE_REGISTER 0x00 // Địa chỉ register cho nhiệt độ #define Slave_ID 0 ModbusMaster node; void setup() { Serial.begin(9600); node.begin(0,Serial); } void loop() { int temperature = random(0, 100); // Giả lập nhiệt độ node.writeSingleRegister(TEMPERATURE_REGISTER, temperature); // Gửi dữ liệu nhiệt độ Serial.println("transmission temperature:"); Serial.println(temperature); delay(1000); } code slave #include #define TEMPERATURE_REGISTER 0x00 // adresse register temperat #define Slave_ID 1 ModbusSlave node; void setup() { Serial.begin(9600); node.begin(SLAVE_ID, Serial); // Khởi tạo node Modbus với ID là SLAVE_ID và sử dụng Serial để giao tiếp } void loop() { int temperature; int a; uint8_t vfdonoff= node.readHoldingRegisters(TEMPERATURE_REGISTER, 1); delay(25); // nếu đọc trạng thái thành công if(vfdonoff == node.ku8MBSuccess) { a = node.getResponseBuffer(vfdonoff); Serial.println("data temperature"); Serial.print(a); } else{ Serial.print("ERROL"); Serial.println(a); } delay(1000); }

You need to check your sensor datasheet the way you will find

Thank you for support. Sure, Next uploaded video will be 1 master and multi salves.

Dear Shahid here is your requested video. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-X8VxQ7lCWKc.html

Modscan me option hota hai ID and register type select krny ka

@@JPLearning thank you for reply sir. lekin sir code error 226 kyu de raha hai jab mai value integer mai send kr raha hu or slave (node id) bhi bana rakhi hai mene 1 or holding register bhi banaya hai phir bhi error aa raha hai

Dekhna hoga aesy samjh nahi araha mjhy.

Jese har sensor ka koi hardware interface hota hai example (Digital, Analog, I2C, SPI Protocols) isi tarha se RS-485 ek hardware protocol hai jisky benefits alag hen or Industrial me zyadatar use hota hai.

I can only guide you to do this.

@@JPLearning thank you sir

You need to just change your pins configurations or may be you need to use Serial2 OR HardwareSerial library in ESP32

Thank you for your answer. I tried a lot of things for one month and its not working. I dont know what to try more. I have this example that didn't work on ESP32 but it's working on Arduino perfectly. I try to search another example with library ModbusRTU.h but it's not working at all on ESP32 and in Arduino I can see some data. I attach the code: #include #define baud 9600 #define timeout 1000 #define polling 200 #define retry_count 10 #define TxEnablePin 15 enum { PACKET1, TOTAL_NO_OF_PACKETS }; Packet packets[TOTAL_NO_OF_PACKETS]; packetPointer packet1 = &packets[PACKET1]; unsigned int volt[2]; long time_past=0; void setup() { pinMode(7,INPUT); Serial.begin(9600); Serial2.begin(9600, SERIAL_8N1, 27, 26); modbus_construct(packet1, 2, READ_HOLDING_REGISTERS, 3846, 1, volt); modbus_configure(&Serial2, baud, SERIAL_8N1, timeout, polling, retry_count, TxEnablePin, packets, TOTAL_NO_OF_PACKETS); time_past = millis(); } void loop() { modbus_update(); if((millis()-time_past) >= 500) { Serial.print("Voltage: "); Serial.print(volt[0] / 10.0f); Serial.println(" V"); Serial.println(); time_past = millis(); } } And the other code is with different library is: #include #include float InttoFloat(uint16_t Data0,uint16_t Data1) { float x; unsigned long *p; p = (unsigned long*)&x; *p = (unsigned long)Data0

Just try this code it's 100% working code with my VFD on ESP32. Change pins, addresses and settings accordingly. Note: You need to install ModbusMaster.h library first. #include #include HardwareSerial hardwareSerial(1); ModbusMaster node; #define MAX485_DE_RE 14 #define RXD2 16 #define TXD2 17 void preTransmission() { digitalWrite(MAX485_DE_RE, 1); } void postTransmission() { digitalWrite(MAX485_DE_RE, 0); } // VFD Parameters #define ID_meter 1 // Trip Information #define Reg_TripInfo 0x2100 // Output Frequency #define Reg_F 0x2103 // Output Current #define Reg_I 0x2104 // Output Voltage #define Reg_V 0x2106 // Inverter status #define Reg_InverterStatus 0x2101 #define Total_of_Reg 5 uint16_t Reg_addr [Total_of_Reg] = { Reg_TripInfo, Reg_F, Reg_I, Reg_V, Reg_InverterStatus, }; double All_DATA [Total_of_Reg]; bool statusRead = false, voltageRead = false; void setup() { Serial.begin(9600); Serial.println(" ESP Start."); hardwareSerial.begin(9600, SERIAL_8N2, RXD2, TXD2); node.begin(ID_meter, hardwareSerial); node.preTransmission(preTransmission); node.postTransmission(postTransmission); pinMode(MAX485_DE_RE, OUTPUT); delay(5000); } void loop() { GET_All_DATA(); String data = "Data_" + String(All_DATA[4]) + "_" + String(All_DATA[1]) + "_" + String(All_DATA[2]) + "_" + String(All_DATA[3]) + "_" + String(All_DATA[0]); Serial.println(data); } double Read_Data(uint16_t REG) { uint8_t result, j; double value = 0; byte dataReadLength = 1; uint16_t data[dataReadLength]; // result = node.readInputRegisters(REG, dataReadLength); result = node.readHoldingRegisters(REG, dataReadLength); ///< Modbus function 0x04 Read Input Registers //Serial.println("result: " + String(result, HEX) + ", " + String(result)); if (result == node.ku8MBSuccess) { for (j = 0; j < dataReadLength; j++) data[j] = node.getResponseBuffer(j); value = data[0]; Serial.println("value: " + String(value, HEX) + ", " + String(value)); return value; } else { Serial.println("Read data fail and address: " + String(REG, HEX) + ", " + String(REG)); return -1; } } void GET_All_DATA() { Serial.println(); for (byte i = 0; i < Total_of_Reg ; i++) { //Serial.println(" Reg_addr[" + String(i) + "]: " + String(Reg_addr[i], HEX) + ", " + String(Reg_addr[i])); All_DATA[i] = Read_Data(Reg_addr[i]); //Serial.println("All_DATA[" + String(i) + "]: " + String(All_DATA[i], HEX) + ", " + String(All_DATA[i])); delay(100); } Serial.println(); }

THANK YOU SO SO MUCH SIR!!! It worked perfectly.@@JPLearning

@@JPLearning Sir I have another cuestion. Please if I want to write a register, I have only to execute this line "node.writeSingleRegister(address,lenght)"? And where I put my value to write it in my device? Thank you for your help.

You're welcome!

I already showed how you can code for RX TX. if you have specific issue let me know then I can help you.

I want to send 3 temperatures from sleeve 1,2,3 to the master. It's better to use max485 which has 2 pin rx tx or 4 pin which has de re pin@@JPLearning

First you need to set unique slaveID for all 3 sensors like(1,2,3) and then you can read all 3 sensors from 1 max485 module. Please watch this video and you can better understand Video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-X8VxQ7lCWKc.html

Sorry I don't understand what you are asking?

This video is just showing simple demo to share data with RS-485 modules. You can see my another videos on RS-485 and Modbus.

Please share more info of communication parameters like communication configurations, Modbus information.

@@JPLearning it's leafwetness sensor manufactured by chaines company jxct it provided user manual with inquire frame 0x01 0x03 0x00,0x20 0x00,0x02 0xC5 0xC1 for temperature and humidity four wire connector vcc, GND, A,B I am using arduino uno with rs485 to ttl converter

Use this whole code just change TX, RX, DE and RE pins according to your H/W connections. #include #include // GPIO Pins byte TX_PIN = D2, RX_PIN = D1; byte DE_PIN = D6, RE_PIN = D5; SoftwareSerial Soft_Serial(RX_PIN, TX_PIN); ModbusMaster node; // Variables #define Sensor_ID 1 #define Reg_Address 0x0020 // for Humidity and Temperature float Humidity, Temperature; void preTransmission() { digitalWrite(DE_PIN, HIGH); digitalWrite(RE_PIN, HIGH); } void postTransmission() { digitalWrite(DE_PIN, LOW); digitalWrite(RE_PIN, LOW); } void setup() { Serial.begin(115200); Soft_Serial.begin(9600); pinMode(DE_PIN, OUTPUT); pinMode(RE_PIN, OUTPUT); node.begin(Sensor_ID, Soft_Serial); node.preTransmission(preTransmission); node.postTransmission(postTransmission); delay(1000); Serial.println(" Welcome to JP Learning "); } void loop() { Read_Data(Reg_Address); Serial.println(" Leaf Humidity = " + String(Humidity, 2) + " %"); delay(100); Serial.println("Leaf Temperature = " + String(Temperature, 2) + " °C "); delay(2000); } void Read_Data(int Reg_Addr) { uint8_t result, j; long value = 0; byte dataReadLength = 2; uint16_t data[dataReadLength]; // Disable watchdog reset ESP.wdtDisable(); result = node.readHoldingRegisters(Reg_Addr, dataReadLength); Serial.println("result: " + String(result, HEX) + ", " + String(result)); // Enable watchdog reset ESP.wdtEnable(1); if (result == node.ku8MBSuccess) { for (j = 0; j < dataReadLength; j++) { data[j] = (node.getResponseBuffer(j)); Serial.println("data[" + String(j) + "]: " + String(data[j], HEX) + " " + String(data[j])); } String dataTemp = String(data[0], HEX); Serial.println(" dataTemp = " + dataTemp); int value = hexToDec(dataTemp); Serial.println(" value = " + String(value)); Humidity = float(value) / 10; dataTemp = String(data[1], HEX); Serial.println("dataTemp = " + dataTemp); value = hexToDec(dataTemp); Serial.println("value = " + String(value)); Temperature = float(value) / 100; } else { Serial.print("Connect modbus fail. REG >>> "); Serial.println(Reg_Addr); // Debug delay(1000); } } int hexToDec(String hexString) { int decValue = 0, nextInt; for (int i = 0; i < hexString.length(); i++) { nextInt = int(hexString.charAt(i)); if (nextInt >= 48 && nextInt = 65 && nextInt = 97 && nextInt

@@JPLearning thanks for help I will use this code again thank you very much

Most welcome and keep supporting me.

For what?

@@JPLearning leafwetness sensor

Please try this code #include // GPIO Pins byte TX_PIN = D2, RX_PIN = D1; byte DE_PIN = D6, RE_PIN = D5; SoftwareSerial Soft_Serial(RX_PIN, TX_PIN); // Variables byte no_Byte, incomingByte[9] = { 0 }; byte sendBuffer[] = { 0x01, 0x03, 0x00, 0x20, 0x00, 0x02, 0xC5, 0xC1 }; float humidity, temperature; void setup() { Serial.begin(115200); Soft_Serial.begin(9600); pinMode(DE_PIN, OUTPUT); pinMode(RE_PIN, OUTPUT); delay(1000); Serial.println(" Leaf Humidity and Temperature Monitor "); } void loop() { read_Modbus(); if (no_Byte >= 9) { String incomingBytesInString[no_Byte]; // Serial.println(" no_Byte = " + String(no_Byte)); for (int i = 0; i < no_Byte; i++) { // Serial.print("incomingByte[" + String(i) + "] = "); // Serial.println(String(incomingByte[i]) + " " + String(incomingByte[i], HEX)); if (String(incomingByte[i]).length() == 1) incomingBytesInString[i] = "0" + String(incomingByte[i], HEX); else incomingBytesInString[i] = String(incomingByte[i], HEX); } String dataTemp = incomingBytesInString[3] + incomingBytesInString[4]; Serial.println(" dataTemp = " + dataTemp); int value = hexToDec(dataTemp); Serial.println("value = " + String(value)); humidity = float(value) / 10; dataTemp = incomingBytesInString[5] + incomingBytesInString[6]; Serial.println("dataTemp = " + dataTemp); value = hexToDec(dataTemp); Serial.println("value = " + String(value)); temperature = float(value) / 100; Serial.println(" Humidity = " + String(humidity, 2) + " %"); Serial.println("Temperature = " + String(temperature, 2) + " °C "); no_Byte = 0; } delay(5000); } void read_Modbus() { // Transmition Enable digitalWrite(DE_PIN, HIGH); digitalWrite(RE_PIN, HIGH); // Serial.println(" sizeof(sendBuffer): " + String(sizeof(sendBuffer))); // for (byte i = 0; i < sizeof(sendBuffer); i++) { // Serial.println("Request: " + String(sendBuffer[i], DEC) + " " + String(sendBuffer[i], HEX)); // } // Serial.println(); Soft_Serial.write(sendBuffer, sizeof(sendBuffer)); // Receiving Enable digitalWrite(DE_PIN, LOW); digitalWrite(RE_PIN, LOW); while (Soft_Serial.available() > 0) { // Serial.println(Soft_Serial.read(), HEX); byte temp = Soft_Serial.read(); Serial.println("Response: " + String(temp, DEC) + " " + String(temp, HEX)); incomingByte[no_Byte] = temp; no_Byte++; } } int hexToDec(String hexString) { int decValue = 0, nextInt; for (int i = 0; i < hexString.length(); i++) { nextInt = int(hexString.charAt(i)); if (nextInt >= 48 && nextInt = 65 && nextInt = 97 && nextInt

@@JPLearning ok sir I will try

Are you facing any issues with ESP2?