Saturday, December 18, 2010



DCS is process oriented: it looks at the controlled process (the chemical plant or whatever) as the centre of the universe, and it presents data to operators as part of its job.

SCADA is data-gathering oriented: the control centre and operators are the centre of its universe. The remote equipment is merely there to collect the data--though it may also do some very complex process control!

A DCS operator station is normally intimately connected with its I/O (through local wiring, FieldBus, networks, etc.). When the DCS operator wants to see information he usually makes a request directly to the field I/O and gets a response. Field events can directly interrupt the system and advise the operator.

SCADA must operate reasonably when field communications have failed. The 'quality' of the data shown to the operator is an important facet of SCADA system operation. SCADA systems often provide special 'event' processing mechanisms to handle conditions that occur between data acquisition periods.

Related Posts with Thumbnails