Industrial grade process control using programmable logic controller

Abstract

Programmable Logic Controller (PLC) are presently being widely used in industries for the automation
of various processes involved such as controlling machines or factory assembly lines and complex
process control using advanced control algorithms.

Earlier automation systems had to use thousands of individual relays and cam timers, but all of the
relays and timers within a factory system can often be replaced with a single programmable logic
controller. Today, programmable logic controllers deliver a wide range of functionality, including basic
relay control, motion control, process control, and complex networking, as well as being used in
Distributed Control Systems and SCADA systems

Process controls in industries are mainly of three types:
1. Continuous Linear Control –This includes PID control.
2. Continuous Non-Linear Control-This includes the FUZZY control.
3. Sequential Control

This paper is divided into two parts. In the first part the operation and structure of PLCs is described and
programming of PLCs using ladder logics.

In the second part the PLC is used to implement the three type of control algorithms viz: PID control
(linear control), FUZZY control (Non-linear control) in the backdrop of most commonly encountered
industrial process which is temperature control and sequential control in water treatment plant. The ladder
logics are made and then the observations are recorded for the temperature control.