I have a Raspberry pi 3b that is working as “fish tank controller” with pH and EC/TDS probes connected.
With a python script I send pH and EC/TDS data to a Cayenne dashboards through MQTT.
Everything works, there are 3 gauges with pH, EC and TDS (TDS are calculated via software as EC multiplied by 0.64) and 2 line charts, respectively with pH and EC graph.
Now I would like to add TDS values to the same chart of EC so I clicked on “Settings–>Add Data Point” then “Graph Settings box” appears, I select the device “TDS” in the list and the error “Incompatible Widget” appears.
I can’t figure out why that error appears…TDS is simply the value of “EC multiplied by 0.64” (and rounded to integer value) calculated in the python script and sent through MQTT like EC and pH are.
Where is my mistake?
Thank you, regards.