What is about DCS?

  • Thread starter Form China ,Junfeng Zhou
  • Start date
DCS stands for Distributed Control System. Think of it as a bunch of computers connected by a network. Most Dcs use token ring as a communication protocol, examples include Baileys infi90 system and Honeywell's TDC3000. The wealth of tools and performance sets these systems apart from othe forms of control such as SCADA but that will all soon change.
 
S

Siramet Subpayasomboon

When you think about DCS , You may imagine about hundreds of single loop controller in a box called control unit of Field Control Unit. Function blocks such as PID need configuration work to assign the relation between each block. Cascading between two PID blocks is a kinf configuration I said. Control station also have capability in sequence control but in second or half of second speed . Field Control Unit controls process via I/O modules. Normally remote I/O of DCS is available.
DCS is very good at availability and reliability. There are all level of redundancy from I/O level , I/O bus , power supply to CPU card. Every things will be its couple for backing up.
You can contact function block ( for example , to change PID setting) in control unit via operator station that can be UNIX workstaion , Industrial PC , Windows NT machine. Also on the screen of operator station , you will able to see your process dynamically in form of graphic.

Network that link all Control Stations and Operator Station normaly be redundant. Token Passing is very famous in large DCS.
 
> What's the difference between DCS & PLC?

DCS = Distributed Control System originally replaced analog controllers by numerical control
software Replacing closed loops only. Progressively logic functions were added.
The mother DCS was called "Intelligent Valve" developed by Powell Systems (?) around or in
1970.
PLC = Programmable Logic Controller (this word Controller is probably what mixes you up)were
introduced shortly after the Intelligent Valve.
They replaced relay racks. Progressively numerical closed loops were added.
Today, their mixed capabilities narrows the border line as some may be used solely for
closing loops or performing solely logic.
 
DCS = Distributed Control System originally replaced analog controllers by numerical control software Replacing closed loops only. Progressively logic functions were added. The mother DCS was called "Intelligent Valve" developed by Powell Systems (?) around or in 1970.

PLC = Programmable Logic Controller (this word Controller is probably what mixes you up) were introduced shortly after the Intelligent Valve. They replaced relay racks. Progressively numerical closed loops were added. Today, their mixed capabilities narrows the border line as some may be used solely for closing loops or performing solely logic.
 
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