Introduction to PLC, SCADA A SCADA (supervisory control and data acquisition) is an automation control system that is used in industries such as energy, oil and gas, water, power, and many more. ... It's very common to set up the SCADA systems to also acquire metadata, such as programmable logic controller (PLC) register paths and alarm statistics. What is PLC? Programmable Logic Controller (PLC) is a digital computer used for the automation of various electro- mechanical processes in industries. These controllers are specially designed to survive in harsh situations and shielded from heat, cold, dust, and moisture etc. PLC consists of a microprocessor which is programmed using the computer language. PLCs enable repeatable processes and information gathering. The information gathered can be used as feedback to guide needed changes and improvements to processes, some of which can be performed automatically according to the device’s coding. If further change is desired, a PLU can be reprogrammed, unlike a relay which would need to be rewired. PLCs take up less space, perform more complex tasks and are more customizable than the technologies they replace. As a result, they’ve had a great impact on industry. What is SCADA? Supervisory control and data acquisition (SCADA) is a control system architecture that uses computers, networked data communications and graphical user interfaces for high-level process supervisory management, but uses other peripheral devices such as programmable logic controllers and discrete PID controllers to interface to the process plant or machinery. The SCADA concept was developed as a universal means of remote access to a variety of local control modules, which could be from different manufacturers allowing access through standard automation protocols. In practice, large SCADA systems have grown to become very similar to distributed control systems in function, but using multiple means of interfacing with the plant. They can control large-scale processes that can include multiple sites, and work over large distances. The SCADA concept in control operations: The key attribute of a SCADA system is its ability to perform a supervisory operation over a variety of other proprietary devices.
The accompanying diagram is a general model which shows functional manufacturing levels using computerised control. Referring to the diagram, Level 0 contains the field devices such as flow and temperature sensors, and final control elements, such as control valves. Level 1 contains the industrialised input/output (I/O) modules, and their associated distributed electronic processors. Level 2 contains the supervisory computers, which collate information from processor nodes on the system, and provide the operator control screens. Level 3 is the production control level, which does not directly control the process, but is concerned with monitoring production and targets. Level 4 is the production scheduling level. http://www.justengg.com/