ESP32與PLC RS485 通訊

目的: 測試ESP32與PLC RS485通訊

系統架構

接線

開發板設定

程式

//NodeMCU_32S UART2 -- DVP COM2 RS485 RTU F03 

#include <HardwareSerial.h>

#define RXD2 16

#define TXD2 17

byte inByte[50] ; // 用來儲存收進來的 data byte

//read D0,D1 command : "010310000002C0CB"

byte cmd[]={0x01,0x03,0x10,0x00,0x00,0x02,0xC0,0xCB};

int i=0;

boolean once = false;

void setup() {  

  Serial.begin(115200); 

  // Serial2.begin(baud-rate, protocol, RX pin, TX pin);      

  Serial2.begin(9600, SERIAL_8E1, RXD2, TXD2); //Modbus RTU 9600,8,E,1   

}

void loop(){ 

  if(!once){  

   Serial.println("ESP32 --> DVP PLC");

   for(i=0;i<sizeof(cmd);i++){   //for PC Monitor

    Serial.print(cmd[i],HEX);

    Serial.print(" ");

  } 

   Serial2.write(cmd,sizeof(cmd)); //ESP32 2 PLC

   delay(100); 

   Serial.println(" ");

   Serial.println(" ");

 // PLC Response

 i=0;

 while (Serial2.available()) { //PLC 2 ESP32

    inByte[i++] = Serial2.read();      

  } 

  int len = i; 

  Serial.println("DVP PLC --> ESP32");  

  for(i=0;i<len;i++){   //for PC Monitor

    Serial.print(inByte[i],HEX);

    Serial.print(" ");

 } 

  Serial.println(" ");  

 i=0;

 once = true;

  }//end once 

}

結果