DCS Archives - Instrumentation Tools

Documentation and Change Control of PLC or DCS Systems

S Bharadwaj ReddyNovember 24, 2019December 4, 2019

Complete and accurate documentation is critical to the commissioning and ongoing maintenance and operation of a PLC or DCS system and should be a high priority of design contract administration....

Readings Mismatch between Field & Control Room ? Why

S Bharadwaj ReddyMarch 18, 2019August 20, 2019

Instrumentation maintenance engineer often hears about process value mismatch from field transmitter display reading and control room DCS/PLC reading. Generally we see the readings mismatch between field & DCS happens...

Difference between DCS & PLC Systems

S Bharadwaj ReddyMarch 16, 2019May 23, 2019

DCS stands for Distributed Control System and PLC stands for Programmable Logic Controller. Do you know the Difference between DCS and PLC Systems ? Difference between DCS & PLC Systems...

PLC Connection between Instrument, Junction Box, Marshalling & System Cabinet

S Bharadwaj ReddyJanuary 3, 2019May 26, 2019

A PLC connection represents the signal flow starting from the field transmitters, junction box, marshalling cabinet, system cabinet and Human-Machine Interface for the operator graphic display. PLC Connection between Instrument,...

PLC Digital Signals Wiring Techniques

S Bharadwaj ReddyDecember 16, 2018March 21, 2019

Ina process plant, on/off control is done through the PLC or DCS. The below Figure is an overview of one discrete/digital (on/off) circuit, showing the entire process from the power supply...

PLC Analog Signals Wiring Techniques

S Bharadwaj ReddyDecember 16, 2018August 14, 2019

Unlike the discrete/digital (on/off) circuit, analog signals vary across a range of voltage or current. Taking the same vessel described previously in Digital wiring example, how would the wiring change...

What is Distributed Control Systems (DCS) ?

S Bharadwaj ReddyJanuary 22, 2018July 8, 2019

A radically new concept appeared in the world of industrial control in the mid-1970’s: the notion of distributed digital control. Direct digital control during that era suﬀered a substantial problem:...

How to Troubleshoot a PLC System

S Bharadwaj ReddyOctober 8, 2016March 21, 2019

At this post i will give some basic instructions which are from my personal experience in order to give you a guide for how troubleshooting in automation systems (PLC/DCS) is...

PID Controllers with Output High Select Logic

S Bharadwaj ReddyMarch 26, 2016August 25, 2019

The below figure 1 shows a typical control scheme with two controllers driving the same control valve via high select logic. The controller PIC-1 is the main pressure controller and...

Overview of Split Range Control

S Bharadwaj ReddyMarch 26, 2016March 18, 2019

A very common control scheme is split range control in which the output of a controller is split to two or more control valves. Split Range Control For example: Controller...

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