The function of this is to take serial input from the RX pin via the SoftwareSerial class.
recvCharsWithStartEndMarkers() pulls messages from the buffer and acts accordingly
the relays are energised based on the messages recieved
there are two DS18B20 temperature sensors on different busses. I know that these can be on the same bus but I have decided to separate these. There may be an impact on available memory - I have explored this and there is still plenty of space between heap and stack.
diagram now updated with the RX and TX pins
