- Analog vs Discrete I/O and speed
Application with high speed requirement like packaging lines ,machine controls with large
amount of discrete I/O it is clearly a PLC application and other application that require
large amount of analog I/O such as oil and gas ,metals and mining ,pulp and paper they
require distributed architecture with multiple controllers.It is clearly points to a DCS
2.Coordination of Control
You have an application that is contained with in one controller that might lead to you
towards PLC.If you have an application that is distributed across multiple controllers then
you might lead towards DCS
Alarm management in PLCs are somewhat complex . DCS system are architected to handle large amount of alarms.DCS helps to create alarm management strategy.
PLCs integrated with lower level devices bring that data up in to the controller and possibly to HMI. DCS is architected to bring that device data and its asset optimization information all the way up through to a higher level packages like maximo or SAP.