Contents

6-2 Single-Loop Digital Control 6 2 . 1 Digital Control Schemes 6-2.2 Initial Housekeeping 6-2.3 Data Input 6-2.4 Control Algorithms 6-2.5 Command Output 6-2.6 Modes of Operation

6-3 Programmable Controllers 6 3 . 1 Hardware Overview 6-3.2 Ladder Diagram Programming Summary Problems

7 POWER INTERFACES

Objectives 7-1 Power Operational Amplifier 7-2 Switch-Mode Servo Amplifiers

7-2.1 Principles of Pulse-Width Modulation 7-2.2 Switch-Mode Filter 7-2.3 Switching Diodes 7-2.4 Pulse-Width-Modulation IC 7-2.5 The Transistor Switch

7-3 Thyristor-Based Power Interfaces 7-3.1 Thyristor Devices 7-3.2 Thyristor Triggers 7-3.3 Proportional Power Circuits Summary Problems

8 SYSTEM RESPONSE

Objectives 8-1 System Transfer Functions

8-1.1 Process Control 8-1.2 Servo Control

8-2 Final Value Theorem 8-3 Stability: The Bod6 Plot

8-3.1 An Overview 8-3.2 Gain 8-3.3 Derivative 8-3.4 Integral 8-3.5 Lead 8-3.6 Lag 8-3.7 Second-Order Lag, Underdamped 8-3.8 Gain and Phase Margins