Programming a Secondary (Safety) Heater

[Jim E.]

P3 eX, FW o; 5.0.0.11.

Sometimes heaters fail. With my previous controller, I ran 2 heaters for redundancy, each assigned to their own socket. I programmed each heater with a one-degree difference. That way, if heater 1 failed at the assigned set point of 76, then heater 2 would come to the rescue as soon as the tank reached 75... and I would know heater 1 failed simply by looking at the current temp. If the temp was 75 instead of 76, that meant heater 1 had failed and required replacement... yet my tank temp could never become dangerously low. This is how I programmed my old controller:

If Temp < 75.5 Then HT1 ON
If Temp > 75.8 Then HT1 OFF
If Temp < 74.5 Then HT2 ON
If Temp > 74.8 Then HT2 OFF

Is this (or something similar) possible using programmable logic?