DCS System Layout and its Different Parts
In this article, we discuss the topic on different parts of DCS system layout and its modules like processors & IO cards, marshalling & system cabinets, engineering & operator workstations,...
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Documentation and Change Control of PLC or DCS Systems
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
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
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
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
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
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) ?
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
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
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...