DIFFERENCE BETWEEN DCS AND PLC

The main difference between DCS and PLC as follows:
  • The real-time response of PLC is faster then DCS, where DCS take much longer time to process data than PLC.
  • A few thousand I/O points can be handled by a PLC whereas DCS can handle many thousands of I/O points 
  • Generally for the frequent process changes  DCS is best option than PLC because PLCs are used for processes that will not change often. And, a DCS is the better solutions when the process is complex and requires frequent adjustments or must analyze a large amount of data.
  • PLC is usually used for controlling medium or large scale applications, whereas DCS is used for controlling the entire plant. ·        
  • DCS can handles handsome quantity of I/Os so that it can be used for total plant automation. Where as PLC has own limitations so it generally used for small but for important units, like boiler automation, Make-up compressor automation Etc.
  • PLC is a high-level programming language, is available for creating custom logic. DCS is a custom logic created from the existing function block.
  •  PLC needs customized routines. DCS already fix many algorithms, not to vary among application. 
  • PLC has certain standard libraries that is used for programming.DCS has a function block and faceplate for programming.
  • The system of PLC design to be flexible. DCS system design to make EASY for any process and also for an engineer to operate the process.
  • PLC is faster than DCS.