I'm curious.
I'm a function block guy and I would have answered "subtract the current value from the holding register value".
If the result of the subtraction is positive, the rate of change is positive, but one also gets a value indicating the magnitude of the rate of change. 48.7 - 42.3 = + 6.4
If I use a CMPR (compare) block, my output is strictly boolean - one output is true for greater than, another output is true for equal to, a 3rd output is true for less than. I get no magnitude value with just a compare function.
Do your "compare" function(s) do the same, that is >, or < ?
Or does it give a magnitude result as well?
Dan