Distributed control system architecture
Distributed control system Architecture is the study of the design we generally follow in any DCS. Generally any beginner do confuse between Distributed control system architecture and DCS infrastructure. The Basic difference between both is Distributed Control system architecture tells about the design of the component and their relationship whereas DCS infrastructure describes the actual set of components which make up a system.
You may study about Distributed control system Infrastructure here.
Evolution of DCS
Pneumatic Control System:- These system generally consists of Single loop controllers, which required More Hardware. These systems were Less Accurate and maintenance was Cumbersome for them.
SLPC:- Electronic Controllers, Single/Multi loop, More Hardware
DCS:- Introduction in the 80’s, Microprocessor Based, Graphic User Interface, Interface with Other devices, Availability of Reports & Diagnostics, User Friendly
Process Control – Components
- Transmitter, Control Valves etc:-
Transmitters are set of equipment used to generate and transmit electromagnetic waves carrying messages or signals. Control valves are used for controlling flow of fluid as programmed. These Devices are used in the field generally known as field devices.
- Cables, Junction Box.
From field devices signal is carried threw cables to Junction Box. Generally there are 2 wire, 3 wire, 4 wire type of cables are there to process signal.
- Barriers, Converters etc.
Barriers are used for safety practices from the hazardous conditions to DCS system. Converters are used for the appropriate signal needed to evaluate into DCS system.
- Power Supply Modules
Power supply Module are there to energize DSC Control Panel. They are mainly used to distribute energy to the processor and I/O modules. It generally has a +5 V DC output supply which together with an input voltage supply provides power backup to the system.
DCS system normally works under harsh environment processing data acquisition and execution, where they require the power converters to have good EMC performance, isolation ability and high reliability.
- I/O Cards & Processor
The work of I/O cards/Modules is to transfer data from the components to the field control system of a DCS. The reverse data movement is also taken care by I/O cards. Generally there are seven kinds of I/O Modules.
Analog I/O Modules, Relay I/O Modules, Digital I/O Modules, Multi point Control Analog I/O Modules, Multiplexer Modules, Communication module and communication card.
- Communication Modules
A brief has been given here about communication Modules. Automation companies have a wide portfolio of industrial Ethernet PHYs, RS-485 PROFIBUS and CAN transceivers which help to meet different speed, noise immunity and power requirements. Furthermore, 10/100 Ethernet or Gigabit Ethernet PHYs with the necessary robustness for an industrial system are also available.
A wireless interface can be used to connect modules with control systems. Many solution providers have solutions for all major low power wireless standards in sub 1GHz bands as well as 2.4GHz and other bands and also including security support needed for those subsystems.
- System Communication Bus / Network
you can visit our page about system communication network and different communication buses here.
- Graphic Display Station
In old times CRT screens were common in use. Now a days in industry you will get much use of LED screens rather than old bulky CRT screens.
- Operator Interface – Keyboard/ Touchscreen / Mouse etc.
- System Configuration – Database Builder, Control Configuration Etc.
- Graphic Builder
- History Builder & Report Writer
- Diagnostic Tools
- Logic Editor
- Control Language – User Programmable Software