SCADA
Learn what SCADA means.
The acronym SCADA stands for Supervisory Control and Data Acquisition. It makes reference to a system that collects data from various sensors at, for example, a factory, plant or other remote locations and then sends this data to a central computer tasked with managing and controlling the data.
As a term, SCADA is used to describe management and control solutions in many private and also public industries like Electric Power Systems, Environmental Control Systems, Traffic Signals, Water Management Systems, Mass Transit Systems, and Manufacturing Systems.
SCADA as a System
A working SCADA system has many parts like signal hardware (input and output), controllers, networks, user interface (HMI), communications equipment and software.
The term SCADA refers to the entire central system. This system is the one that monitors all the data gathered from various sensors that can be on the same area or might be miles away.
The remote Terminal Units (RTU) are the brains of a SCADA system, They consist of a programmable logic converter.
The RTU are normally set to specific requirements, but a majority of RTUs allow human intervention as well. For example in a factory, the RTU might control the setting of a conveyer belt but the speed of the conveyor can be changed or overridden by a human operator at any time. The RTU also logs automatically any changes or errors so these can be displayed and analyzed.
SCADA systems are considered closed loop systems and require with relatively little human intervention. A SCADA system will monitor itself and make slight changes to keep functions at an optimum level.
One of the key distinctions of a SCADA process is the ability to monitor an entire system in real time. This is achieved through data acquisitions such as meter readings, checking statuses of sensors, etc, that are communicated to the RTU at regular intervals.
This data is also displayed to a human that can use an interface to override settings or make any necessary changes to the system.
A way to conceive a SCADA is to think of it as a system with many data elements called points. Usually each point is a monitor or sensor. An actual monitor is considered a HARD Data point; applications and software are considered SOFT points. Both hard and soft points provide data elements and these are recorded and logged to create a time stamp or history.
User Interface (HMI)
A SCADA´s user interface is called Human Machine Interface (HMI). This is where the data is processed and displayed in a way that can be viewed and monitored by a human operator. The interface includes controls that allow this individual to interact with the SCADA system.
RTU´s or PLC’s (programmable logic controllers) will usually run a pre programmed process, but monitoring each of them individually can be difficult because they are spread out over the system. HMI’s are an easy way to standardize and facilitate the monitoring multiple RTU’s and PLC’s. The SCADA system communicates with PLC’s throughout the system network and processes information in a way that can be easily disseminated by the HMI.
If HMI’s are linked to a database, the data gathered from PLC’s or RTU’s can be used to provide graphs on logistic information, trends, schematics for a specific sensor or machine or make troubleshooting guides more accessible.
In the last decade, practically all SCADA systems include an integrated HMI and PLC device this has made running and monitoring a SCADA system an extremely simple affair.
SCADA Components: Hardware and software
SCADA systems are an extremely efficient way of running and monitoring processes. They are ideal for small applications like climate control and can also be used in large applications like those tasked with monitoring and controlling mass transit systems or nuclear power plants.
SCADAs can be found in open and non proprietary protocols. The smaller systems are very affordable and may be combined with specific components or bought as a complete system. The same goes for large systems that can be created with off the shelf components if needed.
SCADA removes the need for custom made software development, its system software can be easily configured, making it effective for almost any application.
