How to track temperature trend

[Colin]

It is easier than that. If you are only interested in looking every two hours then every two hours send the temperature to a function node. In the function node you will save the current value to a node context variable. That means that also in the function node you can pick up the previous value and do the comparisons required to decide what to do. Look at the docs on writing functions to see how to save a value to the node context.