co2 sensor working

arduino/co2_sensor/src/main.cpp

 #include <Arduino.h>
-#include <HardwareSerial.h>
+//#include <HardwareSerial.h>
 HardwareSerial co2_serial(2); // RX2 = pin IO16, TX2 = pin IO17
 
+// #define RXD2 16
+// #define TXD2 17
 unsigned char hexdata[9] = {0xFF, 0x01, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00, 0x79}; //Read the gas density command /Don't change the order
 void setup()
 {
@@ -11,18 +13,30 @@ void setup()
     {
         delay(1);
     }
+    Serial.println("setup Serial1 ok");
     co2_serial.begin(9600);
+    // Serial2.begin(9600, SERIAL_8N1, RXD2, TXD2);
+    // while (!Serial2)
+    while (!co2_serial)
+    {
+        delay(1);
+    }
+    Serial.println("setup Serial2 ok");
 }
 
 void loop()
 {
     co2_serial.write(hexdata, 9);
+    // delay(500);
+    // Serial2.write(hexdata, 9);
     delay(500);
 
     for (int i = 0, j = 0; i < 9; i++) {
         if (co2_serial.available() > 0) {
+        // if (Serial2.available() > 0) {
             long hi, lo, CO2;
             int ch = co2_serial.read();
+            // int ch = Serial2.read();
 
             if (i == 2) {
                 hi = ch;