Standard PID literature provides several ways to define a PID controller. In general, PID controllers are classified using the following forms.

Academic Form

In the Academic form, the proportional parameter P actuates on the integral I and derivative D terms, as represented by the following equation:

The algorithms implemented by the PID VIs are based on the Academic form with time expressed in minutes.

Parallel Form

In the Parallel form, the three parameters P, I, and D are independent of each other and control each interaction. This form also is referred to as non-interacting PID. The Parallel form is represented by the following equation:

Series Form

In the Series form, the parameters are coupled and in series with each component, as represented by the following equation:

Converting Topologies

You can use the PID Structure Conversion VI to convert a PID controller from one topology, or form, to another.