There are two topics that can help you:
-
(Setting up upper & lower limits in PIDs)
Maurice shows an example to limit the output value. -
(Converting 4-20ma signal to actual value using a program)
Maurice shows an example of how to use the straight line formula to convert signals and, of course, it can be used to convert the 0% / 100% PID output to 35Hz / 50Hz (58.33% / 83.33% )