Answer / sumith

The main difference is that
the PLC has one processor(it has limitations for memory
space) and it can used to control one plant or 2 small plants.
The DCS has many processors and it can be used for control
many plants at one time.

Answer / sandip patel

plc has central controller where as dcs has dictributed control.
scanning time of the dcs is more than plc.

Answer / karikhul

plc is centralized controller while dcs distributive.plc has 1 processor card n dcs has 2 processor cards if one fails means v can copy d content frm one 2 another jst lyk master n slave. so it wont disturb d plant also.

Answer / shinde k v

plc means programmable logic control which has fixed
program .dcs means distributed control system which
distribute functionally and physically.

Answer / goutam

The main difference is that PLC needs an external SCADA s/w for process visualization bt in DCS scada is inbuilt.

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Q1: Consider part of a control loop, which excludes the transmitter, consisting of a process, a controller and a control valve which may be represented by two dead times of 0.5 min each and three exponential lags of 0.8 min., 1.0 min. and 1.5 min. respectively. We wish to express this system as an overall first order plus dead time (FOPLD) model ie gain, time constant and process dead time. (We will see later that this is often done, to simplify controller tuning). For this exercise, gain is considered to be 1.0. (A) If the transmitter is a flow transmitter whose behaviour can be described by a dead time of 0.2 min. and an exponential lag of 0.5 min. in terms of the overall dead time and overall first order lag how can the system behaviour be approximated ? Overall dead time = Overall time constant = (B) If the transmitter is a temperature transmitter with a temperature sensor in a protecting well whose behaviour can be described by a dead time of 0.7 min. and an exponential lag of 15 min. how can the overall system behaviour be approximated now? Overall dead time = Overall time constant =

0 Answers  

tell me the field & lab calibration procedure step by step with diagram of pressure gauge, pressure switch, pressure transmitter, temperature switch, level switch, flow switch, flow transmitter, temperature transmitter, temperature indicator, flow indicator, level indicator, control valve, thermocouple, pressure indicator (digital & analogue),

0 Answers