Introduction to SCADA

Supervisory Control and Data Acquisition (SCADA) - Learn how to manage, control and monitor your facilities to stay on time, stay on budget and increase profitability!

1. How This Tutorial Will Help You

SCADA monitoring and control can save you a lot of money and increase profitability, but the implementation can be a sinkhole of cost overruns, delays and limited capabilities. This Tutorial (and its accompanying video) will explain the keys of SCADA technology, give you guidelines for rating various technology and help you decide what kind of SCADA system is best for your needs.

First, we will cover various elements of SCADA technology that apply to its use and implementation, and how it can benefit you. We'll address where SCADA is used, what its value is to you, and how real-time monitoring and control increases efficiency and maximizes profitability.

We'll then look at how typical SCADA systems work. We will explore the world's simplest SCADA system, Data Acquisition, Data Communication, Data Presentation, and Control which are all elements of a typical application.

Next we'll explore how to evaluate SCADA systems and hardware. There can be quite a bit to consider. This includes the two most important components of your SCADA system, sensors and networks, what to look for in a SCADA RTU (Remote Telemetry Unit), and what to look for in a SCADA Master station.

Finally, we will tie together many of these concepts by taking a look at a T/Mon NOC - An Integrated SCADA Monitoring and Control Solution. We'll evaluate whether a T/Mon NOC will work for you, what real people who use T/Mon NOC say about it, why you need help with your SCADA implementation, and what to do next with all of this information.

2. What Is SCADA, and What Can It Do for You?

SCADA is not a specific technology, but a type of function. SCADA stands for Supervisory Control and Data Acquisition - any device that gets data about a system in order to control that system is a SCADA application.

A SCADA application has two elements:

  1. The process/system/machine you want to monitor and control - this can be a power plant, a water system, a network, a system of traffic lights, or anything else.
  2. A network of intelligent devices that interfaces with the first system through sensors and control outputs. This network, which is the SCADA system, gives you the ability to measure and control specific elements of the first system.

You can build a SCADA system using several different kinds of technologies and protocols. This white paper will help you evaluate your options and decide what kind of SCADA system is best for your needs.

Where Is SCADA Used?

You can use SCADA to manage any kind of equipment. Typically, SCADA systems are used to automate complex industrial processes where human control is impractical - systems where there are more control factors, and more fast-moving control factors, than human beings can comfortably manage. Around the world, SCADA systems control:

As I'm sure you can imagine, this very short list barely hints at all the potential applications for SCADA systems. SCADA is used in nearly every industry and public infrastructure project - anywhere where automation increases efficiency.

What's more, these examples don't show how deep and complex SCADA data can be. In every industry, managers need to control multiple factors and the interactions between those factors. SCADA systems provide the sensing capabilities and the computational power to track everything that's relevant to your operations.

What's the Value of SCADA to You?

Maybe you work in one of the fields I listed; maybe you don't. But think about your operations and all the parameters that affect your bottom-line results:

These are questions that proper monitoring and visibility can help answer. The bottom line value depends on the proper application of the right solution to these questions.

Real-Time Monitoring and Control Increases Efficiency and Maximizes Profitability

Ask yourself enough questions like that, and I'm sure you can see where you can apply a SCADA system in your operations. But I'm equally sure you're asking "So what?" What you really want to know is what kind of real-world results you can expect from using SCADA.

Here are few of the things you can do with the information and control capabilities you get from a SCADA system:

A SCADA system gives you the power to fine-tune your knowledge of your systems. You can place sensors and controls at every critical point in your managed process (and as technology improves, you can put sensors in more and more places). As you monitor more things, you have a more detailed view of your operations - and most important, it's all in real time.

So even for very complex manufacturing processes, large electrical plants, etc., you can have an eagle-eye view of every event while it's happening - and that means you have a knowledge base from which to correct errors and improve efficiency. With SCADA, you can do more, at less cost, providing a direct increase in profitability.

3. How SCADA Systems Work

A SCADA system performs four functions:

  1. Data acquisition
  2. Networked data communication
  3. Data presentation
  4. Control

These functions are performed by four kinds of SCADA components:

  1. Sensors (either digital or analog) and control relays that directly interface with the managed system.
  2. Remote telemetry units (RTUs). These are small computerized units deployed in the field at specific sites and locations. RTUs serve as local collection points for gathering reports from sensors and delivering commands to control relays.
  3. SCADA master units. These are larger computer consoles that serve as the central processor for the SCADA system. Master units provide a human interface to the system and automatically regulate the managed system in response to sensor inputs.
  4. The communications network that connects the SCADA master unit to the RTUs in the field.

The World's Simplest SCADA System

The simplest possible SCADA system would be a single circuit that notifies you of one event. Imagine a fabrication machine that produces widgets. Every time the machine finishes a widget, it activates a switch. The switch turns on a light on a panel, which tells a human operator that a widget has been completed.

Obviously, a real SCADA system does more than this simple model. But the principle is the same. A full-scale SCADA system just monitors more stuff over greater distances.

Let's look at what is added to our simple model to create a fullscale SCADA system:

Data Acquisition

First, the systems you need to monitor are much more complex than just one machine with one output. So a real-life SCADA system needs to monitor hundreds or thousands of sensors. Some sensors measure inputs into the system (for example, water flowing into a reservoir), and some sensors measure outputs (like valve pressure as water is released from the reservoir).

Some of those sensors measure simple events that can be detected by a straightforward on/off switch, called a discrete input (or digital input). For example, in our simple model of the widget fabricator, the switch that turns on the light would be a discrete input. In real life, discrete inputs are used to measure simple states, like whether equipment is on or off, or tripwire alarms, like a power failure at a critical facility.

Some sensors measure more complex situations where exact measurement is important. These are analog sensors, which can detect continuous changes in a voltage or current input. Analog sensors are used to track fluid levels in tanks, voltage levels in batteries, temperature and other factors that can be measured in a continuous range of input.

For most analog factors, there is a normal range defined by a bottom and top level. For example, you may want the temperature in a server room to stay between 60 and 85 degrees Fahrenheit. If the temperature goes above or below this range, it will trigger a threshold alarm. In more advanced systems, there are four threshold alarms for analog sensors, defining Major Under, Minor Under, Minor Over and Major Over alarms.

Data Communication

In our simple model of the widget fabricator, the "network" is just the wire leading from the switch to the panel light. In real life, you want to be able to monitor multiple systems from a central location, so you need a communications network to transport all the data collected from your sensors.

Early SCADA networks communicated over radio, modem or dedicated serial lines. Today the trend is to put SCADA data on Ethernet and IP over SONET. For security reasons, SCADA data should be kept on closed LAN/WANs without exposing sensitive data to the open Internet.

Real SCADA systems don't communicate with just simple electrical signals, either. SCADA data is encoded in protocol format. Older SCADA systems depended on closed proprietary protocols, but today the trend is to open, standard protocols and protocol mediation.

Sensors and control relays are very simple electric devices that can't generate or interpret protocol communication on their own. Therefore the remote telemetry unit (RTU) is needed to provide an interface between the sensors and the SCADA network. The RTU encodes sensor inputs into protocol format and forwards them to the SCADA master; in turn, the RTU receives control commands in protocol format from the master and transmits electrical signals to the appropriate control relays.

Data Presentation

The only display element in our model SCADA system is the light that comes on when the switch is activated. This obviously won't do on a large scale - you can't track a lightboard of a thousand separate lights, and you don't want to pay someone simply to watch a lightboard, either.

A real SCADA system reports to human operators over a specialized computer that is variously called a master station, an HMI (Human-Machine Interface) or an HCI (HumanComputer Interface).

The SCADA master station has several different functions. The master continuously monitors all sensors and alerts the operator when there is an "alarm" - that is, when a control factor is operating outside what is defined as its normal operation. The master presents a comprehensive view of the entire managed system, and presents more detail in response to user requests. The master also performs data processing on information gathered from sensors - it maintains report logs and summarizes historical trends.

An advanced SCADA master can add a great deal of intelligence and automation to your systems management, making your job much easier.


Unfortunately, our miniature SCADA system monitoring the widget fabricator doesn't include any control elements. So let's add one. Let's say the human operator also has a button on his control panel. When he presses the button, it activates a switch on the widget fabricator that brings more widget parts into the fabricator.

Now let's add the full computerized control of a SCADA master unit that controls the entire factory. You now have a control system that responds to inputs elsewhere in the system. If the machines that make widget parts break down, you can slow down or stop the widget fabricator. If the part fabricators are running efficiently, you can speed up the widget fabricator.

If you have a sufficiently sophisticated master unit, these controls can run completely automatically, without the need for human intervention. Of course, you can still manually override the automatic controls from the mmaster station.

In real life, SCADA systems automatically regulate all kinds of industrial processes. For example, if too much pressure is building up in a gas pipeline, the SCADA system can automatically open a release valve. Electricity production can be adjusted to meet demands on the power grid. Even these real-world examples are simplified; a full-scale SCADA system can adjust the managed system in response to multiple inputs.

4. How to Evaluate SCADA Systems and Hardware

SCADA can do a lot for you - but how do you make sure that you're really getting the full benefits of SCADA? Evaluating complex systems can be tricky - especially if you have to learn a new technology while still doing your everyday job.

But you've got to be able to make an informed decision, because the stakes are incredibly high. A SCADA system is a major, business-to-business purchase that your company will live with for maybe as long as 10 to 15 years. When you make a recommendation about a permanent system like that, you're laying your reputation on the line and making a major commitment for your company.

And as much as SCADA can help you improve your operations, there are also some pitfalls to a hasty, unconsidered SCADA implementation:

So let's go over some guidelines for what you should look for in a SCADA system.

What to Look for in a SCADA RTU

Your SCADA RTUs need to communicate with all your on-site equipment and survive under the harsh conditions of an industrial environment. Here's a checklist of things you should expect from a quality RTU:

What to Look for in a SCADA Master

Your SCADA master should display information in the most useful ways to human operators and intelligently regulated your managed systems. Here's a checklist of SCADA master must-haves:

5. T/Mon LNX - An Integrated SCADA Monitoring and Control Solution

Our company, DPS Telecom, manufactures T/Mon LNX, a master unit that serves as the core of an integrated SCADA system for all your equipment.

T/Mon LNX can meet all the criteria I've listed for a superior SCADA master.. and can do a whole lot more.

What Can T/Mon LNX Do for You?

Actually, this list just scratches the surface of T/Mon LNX's capabilities. For more information about what T/Mon LNX can do for you, send a quick email to our Sales team.

How Do You Know That T/Mon Will Work for You?

T/Mon LNX is not a new or untested product. T/Mon units have been in the field for years, successfully performing for clients who need stable, bulletproof monitoring and control to support their mission-critical operations.

What Do Real People Who Use T/Mon Say?

"DPS Telecom gave us a reliable way of accessing a variety of equipment, regardless of the brand or provider. We now have a common interface for our existing system."
-Harold Moses, KMC Telecom
"DPS told us we didn't have to pay if it didn't work. It works and it's sweet."
-Glenn Lippincott, Southern Company
"It's hard to find companies with the intelligence and aptitude to meet the customer's exact needs, and I believe that is what DPS is all about."
-Lee Wells, Pathnet

Why You Need Help With Your SCADA Implementation

Implementing an SCADA system can seem deceptively easy - you just look on the Web, find a few vendors, compare a few features, add some configuration and you're done, right?

The truth is, developing a SCADA system on your own is one of the riskiest things you can do. Here are some of the typical problems you might face if you don't get expert advice when you're designing your system:

"I'm Ready to Take a Serious Look at T/Mon - What Do I Do Next?"

Call Ron Stover at 1-800-693-0351 or email him at rstover@dpstele.com and ask for a free consultation on T/Mon SCADA solutions. Ron will be happy to discuss your specific requirements and answer any questions your have.