What is discrete PID controller?
The Discrete PID Controller block implements a PID controller (PID, PI, PD, P only, or I only). The block is identical to the PID Controller block with the Time domain parameter set to Discrete-time .
How do you discretize a PID controller?
A straightforward way to discretize this controller is to convert the integral and derivative terms to their discrete-time counterpart. There are commonly 3 variations to do so, by means of forward Euler, backward Euler, and trapezoidal methods.