Instrumentation Question:

Answer #1
If we have more I/o's in digital signals than analogue signals normally we choose DCS....and vice versa.

Answer #2
PLC IS JUST MONITORING AND REPEAT THE PROCESS BUT DCS CAN CONTROL THE PROCESS,,,PLC IS RELAY CONCEPT,,,,DCS IS WIRING CONCEPT

Answer #3
For graphics and control logic there is single data base in DCS system, but in plc we need to implement two times i.e separate for these two.
DCS can handle more i/o\\'s but scanning time will be high as compared to PLC.

Answer #4
In PLC the input scan rate is 10 ms but in dcs the input scan rate is more than 100ms that's why PLC has ability to run drives and motors effectively these requires fast communication PLC has a simple PID control dcs uses advanced PID control