Instrumentation and control systems are the heart of all processing industries. No process can run without the aid of instrumentation. Instrumentation and control concepts have undergone a drastic change over the past few years.This book is aimed at graduate level students of instrumentation and process control (electrical and electronics and instrumentation and control disciplines). The book is made up of eight chapters. The first three are devoted to transducers. In these chapters, the emphasis is on transducer signal selection, pneumatic transmitters, smart transmitters, special class thermocouple, nucleonic level gages, and electronic level gages. In the chapter on telemetry, pneumatic transmissions are covered in addition to the usual topics. In the chapter Process Control, three element control systems are described through examples of boiler drum level control. Finally, in Recent Developments & Microprocessor Based Instrumentation System, development of PLC and distributed control systems and instrumentation communication protocol are sdescribed in detail with suitable examples.