Overview of System Architecture

Question 1

What is System Architecture?

Answer 1

A design concept of a control system that outlines how the system is built and how it functions. System architecture includes hardware used, what each component does and how it is all networked together.

Question 2

What are the 3 typical functions that are performed at the Enterprise Level?

Answer 2

1) Production scheduling
2) Inventory management
3) Regulatory agency reports

Question 3

List 3 typical functions performed at the Operations/Engineering Level of a process
control system.

Answer 3

1) Operator control room visualization
2)Engineering/ maintenance access
3) Process data historian and alarming

Question 4

List 3 typical functions performed at the Controller Level of a process control system.

Answer 4

1) Continuous process control
2) Logic control
3) Emergency shutdown system control

Question 5

List 3 typical functions performed at the Field/Process Level of a process control
system

Answer 5

1) Process measurement
2) Valve actuation
3) Some process control using Foundation Fieldbus devices

Question 6

What are the 3 advantages of using reference architecture?

Answer 6

1) Scalability
2) Ability to use off the shelf communication products to not rely on specific vendors
3) Reference architectures promote re-use of the design work

Question 7

What is ISA SP95?

Answer 7

ISA 95 is a standard based on the Purdue Reference Model that is applied to define the interface between Manufacturing Operations & Control and Business Enterprise level functions.

Question 8

What does SCADA stand for?

Answer 8

Supervisory Control and Data Acquisition

Question 9

What are the 2 key differences between SCADA and DCS?

Answer 9

1) DCS controls systems in a small geographic area for example a plant. A SCADA systems is used to control plants that are more distributed over a large area
2) DCS software and hardware is typically supplied as a package from a single vendor (eg. DeltaV). In SCADA systems components come from different vendors and are unified by a Systems Integrator.

Question 10

What are the 5 layers of the Purdue Reference Model?

Answer 10

1) ERP
2) MES
3) SCADA
4) Controllers
5) I/O Fieldbus

Question 11

What is UNS and what is the disadvantage?

Answer 11

Unified Name Space; a system architecture that works on a cloud with publish and subscribe features. The disadvantage is that if the broker is lost so is all the data. This is why data needs to be backed up.