Difference Between Plc And Dcs r4852

Difference between PLC and DCS (Mr. Atul Anil Aphale) No. 1.

PLC PLC is a digital computer used for automation electromechanical processes.

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PLC is a one unit used to control particular machine or production unit

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PLC is a on/off controller. It Controls the only machine on or off.

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PLC is used Commonly with On\Off (Digital) Control and may be expanded with Analog I\O Modules for Analog Control and used for a Unique Task.

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DCS is used Commonly with Process Control Systems as it is Combined of Many control Cards, PLCs.

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PLC does not have wide range of communication. PLC is basically oriented for one job only, suppose if PLC fails then whole system will shut down.

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DCS have wide range of communication. In DCS there is redundant PLC for each PLC so that if primary system fails then its standby plc takes over the charge.

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PLC has to read all its data itself and to generate o/p accordingly, if the system is big the scan cycle goes high and any changes in i/p could scan & display little late

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DCS have many sub processors who update their data and give summery to DCS, so DCS have to scan only these sub u hence it improves the scan cycle and system becomes faster. Now PLC has also coming with big data handling capacity with low scan cycle.

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In PLC, we can’t change configuration online. We have to go offline to change configuration. In PLC analog control is simple PID control.

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In DCS, parameters can be changed online.

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In DCS simple to advanced PID control up to advanced process control.

Total cost and size is much less than DCS system.

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Total cost and size is higher.

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DCS DCS is a automated control system that is distributed through a machine to provide instructions to different parts of the machine. DCS is number of PLC’s distributed over a control network over the entire plant. DCS controls the many PLC’s at a time.