This PH rod is designed on ATMEGA8 Ic .
On board LDR for light value, Thermister fortemperature value.
It gives Serial data at its Tx pin
PH value  W: depth of rod immersed  L : light value  T temperature value
PH  W  L  T
For testing you can use an USB-TTL device (to be purchased separately) to read the Serial data flow every second.