ABB plc or DCS?

In our plant we are using ABB Master Pieces MP200/1 and two Advant500 series Operator station at CCR-3 (central control room)
while in CCR-1 there is AB system ContolLogix5000 and RSView system
combination.
Can anybody tell me that are we using DCS, SCADA or PLC system ?
I dont know the exect difference between DCS and PLC.
pls. Help me.

Thanks.

PLC vs DCS

I maybe way off here, but I think the significant differences between a PLC (Programable Logic Controller) and DCS (Distributive Contol System) are:

1. How the proccessors scan the I/O.
PLC-in scan top to bottom
DCS-scan all I/O ussually based on change.
2. The refresh speed of the data or scan time.
PLC-Depends on the length of the program, loops, Sub routines, etc...
DCS-Typically more real time data.
3. Cost
PLC-More cost efective on a per I/O basis than DCS.

If I am going to apply a new control system to, for example, a chemical proccess that would tend to be easily upset, I would choose the DCS.
If on the other hand I am adding a package conveying system, a PLC would be more that sufficient. Of course this is an over simplification of the problem, but I think you see my point...


Opinions are like bosses, everybody has one.... )
Daniel Camacho

The ControLogix platform does not scan the way a traditional PLC scans (i.e. top to bottom left to right). The ControLogix allows you to schedule I/O updates based on change-of state, and also provides the opportunity for event-based scheduling of block of logic or subroutines.

MP200 sounds old. DCS or not. Probably the AllenB equipment is better in any way you compare no matter what it's called.