What Is SCADA? How It Works? What Is It Used For?


Since 2006 I have been teaching SCADA software for the two largest global SCADA products as a certified instructor.  Let me share my industry many years of industry knowledge and point of view on what should be important to you when looking at SCADA software products.

Supervisory Control And Data Acquisition systems commonly known as SCADA are the visual representations of what is happening in your plant or process used for centralized control.  Common major features are: Alarms, Trending, Graphics, Communications,  Redundancy, Scripting, Reporting and Security. 

What do Industry Professionals need to know about SCADA?

  • Types of SCADA
  • Common Features
    • Alarms 
    • Reports
    • Trends
    • Security
    • Graphics
    • Connectivity
    • Redundancy
    • Scripting
  • Licensing & Costs
  • Market Share
  • Manufacturers

The global automation industry market size is 214 billion and there is a massive
opportunity for employment.

What is the main function of SCADA?

SCADA allows you to have a single person or operator as they are known in the industry, to monitor a whole plant or process from a centralised control room. This is done through the use of a interactive graphical representation of what the plant looks like on a computer screen.

Here is what a SCADA runtime looks like:

NOTE: The picture above is the example project in CitectSCADA 2018R2

SCADA sits at level 2 of the MES hierarchy which is simply a technology stack of what is in your plant or process, from the physical equipment all the way up to the enterprise resource planning level.

For more information about MES and the MES Hierarchy take a look at this article:
LINK: What is a Manufacturing Execution System (MES)?

What is SCADA used for?

Here are some industrial applications that SCADA is used for:

  • Water & Waste Water (WWW)
  • Power Generation & Distribution
  • Oil & Gas
  • Building Management Systems (BMS)
  • Mining & Minerals
  • Transportation
  • Refrigeration
  • Shipping
  • Aircraft
  • Manufacturing
    • Food & Beverage
    • Mobile Phones
    • Cars
    • Computers
    • And all other manufacturing area

So essentially SCADA is part of the technology stack that is used to run the world and supply everything you use every day from the moment you wake up to the moment you go to sleep. A technology stack is the vertical layers of technologies used to solve complex technical problems.

Here is an example Technology stack for Industrial Automation:

  • Enterprise Software
  • MES Software
  • Process Historian
  • SCADA
  • Programmable Logic Controllers (PLC)
  • Sensors and Instrumentation
  • Plant or Process Equipment

How does SCADA work?

SCADA essentially connects and talks to physical equipment or smart controllers in the plant to tell the plant or process what to do. It then takes this information and represents it in a graphical way to the person or operator in the control room in a more meaningful way. Through SCADA operators are able to turn on and off equipment, areas of the plant or the whole plant or process. They can also change values like temperatures, speeds, levels and flow rates for the equipment as well.

What are the types of SCADA?

There are two major types of SCADA systems, those used for Hard Wired networks and those used for Telemetry networks.  A hard wired network SCADA is one you would see in a Manufacturing plant, Mine site or Building Management System.  Hard wired just means you have physical computer networking cables between all the computers and it is generally in a small geographic area.

NOTE: The diagram above is a simple diagram of a hard wired SCADA only and does not include PLC’s, Equipment, Sensors or any other industry components and is just to show a simple hard wired computer network.  More will be shown in later more advanced articles.

A telemetry network is one that does not use physical computer networking cables and uses data radios instead.  They are used mainly for wide area networks over large geographic areas.  These would be something like Water & Waste water networks (excluding the treatment plants) or Oil and Gas networks.

NOTE: This is a simple network diagram only showing a basic telemetry style solution and does not include RTU’s, Sensors, Equipment or any other components.  These more advanced diagrams will be shown later in more advanced articles.

So why is there a difference?  The main reason is that telemetry networks (computer networks using data radios) have very limited data they can send so the data needs to be monitored closely and prioritised across the network.  They also use different communications protocols to communicate as well that take this into account.

A communications protocol is just how computers talk to each other.  An agreed set of rules just like when you are talking to someone in english.  English is a form of communications protocol and if you think about when you know when it is your turn to speak in a conversation or how priority messages are sent when talking to your friends computers do exactly the same thing.

Now hold on can’t SCADA’s primarily used for hard wired networks also use the same way to talk to telemetry networks as well?  Yes but the features for a Telemetry SCADA are much more advanced and they have many more features that hard wired SCADA’s specifically for radio based networks.  

They work directly and have much more control of the communication protocols like the Distributed Network Protocol (DNP3).  This allows you to control each pump station update times individually and also remotely update them.  We will talk more about this in our telemetry article.

You may use both of them in your plant or processes and Water Treatment plants are a perfect example.  You may use a hard wired SCADA for your Water Treatment plant itself but for your water pumping stations all over a city or region you may use a Telemetry based SCADA.

We will discuss each style of implementation in later articles in more detail and talk about the specific technologies involved.

What are the core features of SCADA?

No matter what type of SCADA you have there are some core features required by them all for use in the industry.  So let’s discuss some of these common features so you understand why they are so important.

Alarms 

The ability to let you know when something is going wrong in the plant is critical to a Supervisory System like a SCADA system.  The ability to alert your operators to know that something may be about to go wrong or has gone wrong so they can intervene means you can keep your plant or process running smoothly and maximize your assets.

Some of the reasons we use alarms are:

  • Hardware failures – Computer hardware
  • Software failures – SCADA software
  • Communications – Connections to controllers and equipment
  • Process related – Related to what you are making or processing
  • Human Error – Related to Operational Staff

We will talk more about alarms in each product that is reviewed on how they handle alarms and what kinds of alarms they have.  Below you will find an example of a live SCADA alarm page.

Reports

SCADA is classified as an operational system that you use to run and monitor your plant or process so reporting is not what it is good at.  You also don’t want to slow down operational systems while someone runs a big report.  For serious reporting tools and also to not affect live operational systems you should use a Process Historian for advanced long term storage or process data and reporting.

That being said most SCADA’s allow some level of inbuilt reporting but not all of them.  If you want a quick snapshot report of what your plant is doing right now then that would be a simple report you could run.  Likewise a downtime report where you are getting information on why the plant or process just stopped and for how long.  Generally these reports will be a page or two and for more advanced analytics use a proper historian.

Here is a simple example report

Trends

Trends are snapshots of what is happening in your plant over time.  So for example if you are making bread and you have an oven that is constantly trying to turn on and off the heat to keep at the right temperature.  This is something you could trend over time.  Trends are critical for both operation of your plant or process as well as for maintaining equipment.  If the oven temperature gets too high the bread is burned and if it is too low for extended time then you only get proofed dough.

So trending is how operators of your plant and maintenance staff keep the plant running at optimal levels.  They can also be used for fault finding when the plant stops or is running abnormally.  You can see when the oven gets too hot the radiant temperature causes equipment nearby to be affected which may make them fail for instance.

Most of the information from the plant is trended not only for the running of the plant but for analysis later on how the plant can be run cheaper and more efficiently.

Here is an example trend page from a live SCADA system.

Security

When I first started teaching in the industry over 15 years ago I was astounded how few people used security in their plants.  Everyone used generic logins with no accountability or the ability to know who needed further training.  

These days those with generic logins or no security are the rarity.  This has been brought on by the connection of enterprises to plants and processes and remote workers using the internet.  This has also brought about the growing risk of threats from the internet and the need for cyber security as well as local user based security.

Most SCADA systems have built-in User and Group level security as well as the ability to link that to your Windows Domain security as well.  Some SCADA’s now also have end to end encryption as well to protect the traffic going between nodes.  

The more information is shared throughout your organisation both locally and geographically you need to be aware of what security you can implement to minimise risk to your sensitive process related data.

If the simple act of logging in on a keyboard is an issue in your plant for whatever reason you can always implement security cards or RFID tags to auto log on operators when they bop on equipment or in the control room.  This can be tied to your physical security measures on building and site entrances as well.  

Graphics

The graphics displayed on the screen are also a primary component of how the information collected in your plant or process is shown to your staff.  A physical pump and be shown with a pump graphic on the screen in different colours depending on the current status of the real world equipment.

The trend for graphics is moving away from bright and flashy screens using heaps of colour are giving away to Abnormal Situation Management (ASM) compliant graphics.  The ASM Consortium has been around for 20+ years and has been providing guidelines for Alarm Management, HMI Graphics and Procedural Practices.  

Human Machine Interface (HMI) screens are basically the computer screen attached to a single piece of equipment in the plant or to a couple of local pieces of equipment that allows for local control.  SCADA is its big brother and allows for plant or process wide control.

The guideline relating to HMI / SCADA graphics can be found here:

LINK: ASM Consotium

The ASM compliant graphics are basically grey only graphics for equipment and with colours only used for alarm states.  While it is much more than that it will give you a basic understanding of graphical differences.  They were designed with operator response times in mind and to declutter computer screens.  We will discuss it more in later articles.

The availability of graphics libraries and page templates is another feature most SCADA products have to increase reuse and standardisation of graphics as well as to minimise future work and maintenance.

Connectivity

The ability for your SCADA system to connect to the equipment in the plant is another critical feature.  There are multiple types of communications that can be done but the main two used in industry are Direct Driver and OPC.

Direct Driver is a communications driver for a specific device made for your SCADA that can only talk to that specific device like a Programmable Logic Controller (PLC), Remote Terminal Unit (RTU) or other smart device.  All of these devices are essentially ruggedised computers specifically designed to use in your plant or process and we will talk about them more in future articles.

OLE for Process Control (OPC) is a generic communications protocol.  It was primarily made as a generic method to connect between different vendor hardware.  This way the OPC Server or communications gateway could be a third party and use direct drivers to connect to all equipment and then anyone that wanted to get data only needed to connect using OPC.

The OPC foundation is the one that makes the specification for OPC and then any company can create a opc server and / or client that uses those standards as a way of connecting and sharing data.

LINK: OPC Foundation

The OPC Training institute does monthly webinars and supplies training which can be found one the link below:

LINK: OPC Training Institute

Redundancy

In 24 hour / 7 days a week operations it is another core requirement to be able to ensure as close to 100% uptime for the SCADA system as possible.  This means that you can not just rely on a single SCADA server to run your system.  If the computer hardware that server is running on breaks then you lose your centralised view of your plant.  This means more labour to run the plant.

So the solution is redundancy in your SCADA system so that you can have many servers that can take over from each other if one server should fail.  All SCADA systems implement some form of redundancy but all redundancy systems are not equal and it is important you check whether that SCADA system has the right redundancy for your plant or process.

Some systems only support dual server redundancy, some support triple redundancy and others support almost unlimited redundancy.  We will discuss this in further detail with each different product as we talk about the pros and cons of each SCADA system.

Scripting

Most major SCADA systems on the market allow for some sort of programming or scripting to allow you to do more complex tasks.  It also allows you to interface through code to other systems and the operating system when needed.

Typically all the SCADA’s also have an API or Web Service interface as well if you wish to connect third party software or custom applications into the SCADA as well to send and receive data or take certain actions.

The coding interface is normally a cut down version of a commercial programming language or a small proprietary coding language.

Licensing & Costs

While the licensing for each SCADA is slightly different, most of them have a point and license type style approach.  That means if you read from the field and oven temperature value regularly this would consume 1 point.

The types of licenses are generally function based where you may get a server license and client license for instance for each type of software.  So you could have a SCADA Server license with 1000 points which means it can run your SCADA server and get 1000 pieces of information from the plant.

As for costs these vary widely and can get complicated for some of the vendors out there with Aveva System Platform licensing being the most complex I have seen and the most expensive.  Where the Ignition SCADA license can be the cheapest for a small install.

Both the pricing and licensing I will go into further detail in the articles directly on each product.

Market Share

The Arc Advisory Groups annual HMI research report is considered the go to for global market share by Vendor.  It only breaks the SCADA and HMI products down by Vendor and not product but typically System Platform below has the largest global market share followed by Plant SCADA and then the rest have smaller market share components.

The last report I saw from them had System Platform at around 25% with Plant SCADA (CitectSCADA) at about 15% to 20% and the rest in single digits.  This is just to give you an understanding of where they were a few years ago.

LINK: Arc Advisory Group – HMI research report

Manufacturers

Aveva Plant SCADA

https://www.aveva.com/en/products/plant-scada/

Formerly known as CitectSCADA and Vijeo Citect this product has been around since 1987 with its first Dos based version and still continues today as a major player in the global market.  It moved to AVEVA with Schneider Electrics reverse takeover of AVEVA in late 2017.  

I am a certified trainer for Citect SCADA and have been since June 2006.  I also ran the national Australian Training Team for many years as well as the global training development and delivery globally for years as well.

Plant SCADA has a single IDE which is a reason why it is simpler to use and understand and has a great help system that not only has the answers you seek but an example of how to do each task.

The product was initially developed in Australia and it had the dominant market share there for many years and its market grew from there to the rest of the world.  The product was made with the end user in the plant in mind and is fairly simple to configure and use by someone new to the industry.  The training is good for the product and in one 4 day course you will be up and running.  

Out of the box without a license you can develop and run a project for 8 hours not connected to real equipment or 20mins connected to real equipment.  You can not do Citect SCADA networking but all other networking to devices is ok until you get a real license.

Aveva System Platform

https://www.aveva.com/en/products/system-platform/

Formally Wonderware System Platform this product has also been around since 1987 and started in the USA in California.  This is where its head office still exists today in Lake Forest.  It was bought by Schneider Electric and then handed across to AVEVA with the reverse takeover as well in 2017.

This product is more technical and object orientated and was built more with System Integrators in mind and can be a bit more complicated to initially learn for someone new to the industry.  It does however have more advanced features and integration with the suite of products that make up System Platform.

Due to the bundle of products that make up System Platform the licensing can be a bit more complicated and expensive than some of the other SCADA systems.  The benefit is the extra features that come along with that.  The help system needs some work and you may spend more time on the phone with support if you are trying to do something more complex.

I am also a certified trainer for System Platform and have been for many years and used to run the APAC delivery of the training with my team.  I was the primary trainer for it and also ran the team of trainers for Schneider Electric.  I still contract train for Schneider to this day delivering training on both System Platform and Plant SCADA.

The training for System Platform is a little longer due to the bundle of tools in the suite of products and you will need to do 2 courses or 8 days training to get a SCADA back and front end up and running and another 4 days for your Historian configuration and client tools.

System Platform trial licenses are only for 30 days and you will have to talk to your account manager for a new one every time it runs out.  This can be a pain and while the license lets you do most things it is a bit annoying.

Schneider Geo SCADA Expert

https://www.se.com/us/en/product-range-presentation/geo-scada-expert/

Formerly known as ClearSCADA this is a telemetry based SCADA developed primarily for radio based wide area networks.  The rest of the products listed here are primarily hard wired SCADA’s with telemetry driver communications drivers.  

Geo SCADA has many more features when it comes to dealing with DNP3 (Distributed Networking Protocol) and even allows you to update firmware remotely in radios.  This product did not go with the reverse takeover of AVEVA and is still part of Schneider Electric.

It is also object orientated in nature and mainly built with vector only graphics so that is maximised the speed of delivery of pages through the data radios and other telemetry communications devices.  This is needed due to the limited bandwidth as discussed above in the article.

Remember it is not uncommon to use Geo SCADA for your telemetry network and another SCADA completed for your hard wired plants.

Inductive Automation Ignition

Ignition is the relatively new kid on the block on the global SCADA scene.  While the company was founded in 2003 they only went really global with their SCADA 5 to 10 years ago enough to start being taken seriously by the major players.

100% of their training is online for free and the simple licensing model that is generally cheaper for small installs then the other players have been the major drivers in their growth.  There is also a built in trial for people which makes it easy for people to download, learn and use quite quickly and cheaply.

They have done well with their marketing as well which has helped them catch up to the bigger players like a product wrapper on the ISA magazines and to members.  ISA we mentioned in the article above as the global organisation that helps with training and setting industry standards.

What makes Ignition unique is that it is truly web browser based and will work with all devices.  There are pros and cons to that but it does mean you don’t need to install client software.  They have done well to make it look good in a browser and you can look at the demo scada on their demo website below.

LINK: Ignition SCADA Demo Website

Inductive Automation is really waking up the bigger players in the market and encouraging them to speed up development in an industry that had stalled a little and lost touch with what customers were asking for.  Ever since I have been in the industry there has been a slow push to more customer driven functionality rather than prescription by vendors who had lost touch at times.

Siemens 

https://new.siemens.com/global/en/products/automation/industry-software/automation-software/scada.html

Siemens is a company that has their fingers in a lot of pies but don’t have a huge market share in the SCADA market.  Their SIMATIC WinCC product range is what they sell and the WinCC Professional for use with their TIA portal, WinCC 7 stand alone SCADA and finally the WinCC OA (Open Architecture).

There is a video half way down the page above that will explain these differences to you if this is your first time using their SCADA products.  Essentially it is WinCC Pro for small implementations and only 1 server, WinCC 7 for medium implementations with multiple servers and more clients, WinCC OA for large installations.

Rockwell

https://www.rockwellautomation.com/en-us/products/software/factorytalk/operationsuite/view.html

FactoryTalk is the marketing brand for the automation software from Rockwell with FactoryTalk View being their SCADA product. Factory Talk View is part of their Factory Talk Operation Suite of products.  Their SCADA sales are driven mainly by their large PLC market share that is slowly changing due to competition and equal features at a cheaper price by most other PLC manufacturers.

While not as popular as some other SCADA products it can be used as a full SCADA system or as a single screen HMI as well as with a pocket version for mobile devices.

Honeywell

https://www.honeywellprocess.com/en-US/explore/products/control-monitoring-and-safety-systems/scada-systems/Pages/experion-scada.aspx

Experion SCADA is Honeywell’s SCADA solution that they have gone 100% virtual or cloud based which has it pros and cons.  All other SCADA products will also work in the cloud as well as locally but this is one of their major selling points.

Performance is the problem with this approach that you don’t notice on small implementations but nothing beats local I/O servers when you are trying to grow a project.  I will let you explore this product more on the link above but be sure to do performance testing on this one prior to committing.

Other Companies

Here is a list of other companies you can look at products for as well:

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