String payload = "{";
              payload += "\"temperature\":"; payload += desp_temp; payload += ",";
              payload += "\"target\":"; payload += target_temp; payload += ",";
              payload += "\"wifi\":"; payload += wifi_quality; payload += ",";
              payload += "\"actuator\":"; payload += actuator_feedback;
              payload += "}";
                                                                                                
              // -------------------   Testing Code
              ModbusSerial.flush();
              ModbusSerial.println(payload);

              delay(500);
              
              //Read the data on the port
              int datalen = ModbusSerial.available();
              Serial.println(datalen);
              String SerialData;
              for (int z = 0; z < datalen; z ++) {
                  SerialData += (char)ModbusSerial.read();
              }

              Serial.print("Data from the Modbus Serial Port : ");
              Serial.println(SerialData);

              //--------------------------

# -*- coding: utf-8 -*-

import serial
import traceback
import time

# Define the serial port
ser = serial.Serial('COM5', 9600 , timeout = 15)
ser.parity = serial.PARITY_EVEN    
ser.flushInput()


#Set the run flag
run = True

#Run while the flag is set
while run:

    try:
        serial_line = ser.readline()
        ser.flushInput()
        print('Serial Data : ' + serial_line)
        print('Sending data to the ESP32')
        ser.write('Hallo Jaco !! ' + '\r\n')
        time.sleep(0.5)
		
    except KeyboardInterrupt:
        print "End"
        run = False        

    except:
        traceback.print_exc()    
	

0
Data from the Modbus Serial Port : 
0
Data from the Modbus Serial Port :
0
Data from the Modbus Serial Port :

Serial Data : {"temperature":28.44,"target":0.00,"wifi":58,"actuator":30}

Sending data to the ESP32
Serial Data : {"temperature":28.44,"target":0.00,"wifi":50,"actuator":30}

Sending data to the ESP32
Serial Data : {"temperature":28.44,"target":0.00,"wifi":62,"actuator":30}