What is the difference between SCADA & DCS system?

Even the two systems actually share the similar philosophies, its have a lot of differences between the two systems.

SCADA systems is an events and data-gathering  based system, so the SCADA main room is your system centre and its where you have your DB to detect any change of state and any sequence of events like alarms , events , etc. that usually transmitted from a field device through communication protocol. which is lead to another issue that the system should be able to handle at any communication failure / device failure.

DCS systems is a process based systems , no main master room , your system is decentralized and distributed all over you facility , its always connected to your data source ( no hassle for provide a secure reliable connection )

however the downside for these systems is it won't alarm you of there is an event change ( no sequence of events ) and it should be latched on and confirmed , configuration for alarms not flexible as SCADA one.

actually there is too much in-detail deferences but as conclusion : both systems are different but what to choose is depend on the client requirements

regards

engr. ahmad tamimi