This paper deals with analysis of main functional diagrams of step PID controllers for electric motor-driven actuators. The main

formulae to calculate the parameters of the diagrams of step PID controllers are presented in the paper. The influence of these

parameters on the transient processes in step controllers and on the output position of the actuator is analyzed. Transient

processes in step controllers with motor-driven actuators are simulated in PI and PID control mode. These transient processes are

compared to the transient processes in continuous controllers. The accuracy of step PID controllers is analyzed, and restrictions

on the parameters of step PID controllers are presented. The diagrams of step PID controllers considered in this paper can be

implemented in the up-to-date PLCs software for automatic control using the electric motor-driven actuators in the control loops.