This book has been designed as a textbook for the students of Electronics and Instrumentation Engineering, Instrumentation and Control Engineering, Mechatronics Engineering and Chemical Engineering courses offered in Technical Universities in India. The first edition of the book published in the year 2006 covered mainly the mathematical modeling of various processes, controller characteristics and tuning, multi loop controls, final control element and selected unit operations. Due to popular demand from students and faculty members of Technical Universities, two more chapters namely Signal Conditioning and Digital Controllers-computer-based control are added in this edition. The book is an outcome of the author`s vast industrial experience and his rich academic background. The book would serve as an extremely useful text for students and faculty, and as a very good reference for the Process Control professionals in industries. About The Author: Prof. K. Krishnaswamy, after graduating Bachelor of Engineering (Electrical) from P.S.G. College of Technology, Coimbatore, Tamil Nadu, has completed Master of Technology (Measurements) from Indian Institute of Technology-Madras, Chennai during 1971. Since then he was working in Steel Authority of India Limited, Rourkela Steel Plant for 26 years and in Salem Steel Plant for about 4 years. He was associated with erection, commissioning, calibration, testing and maint.