How SCADA Systems Work

Section 2: 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. SCADAmaster 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:
SCADA Tutorial • DPS Telecom • 4955 East Yale Avenue, Fresno, CA 93727 • (800) 622-3314 • Fax (559) 454-1688 • www.dpstelecom.com

This RTU Grows with
Your Network
When you’re planning your SCADA
systems, think about the future. You
don’t want to get locked into a system
that’s inadequate for your future needs
— but you don’t want to spend too
much for alarm capacity you won’t
immediately use, either.
The NetGuardian 832A remote
telemetry unit expands its capacity as
your needs change. Install a
NetGuardian at your remote site now,
and get exactly the right coverage for
your current needs.
Then, as your remote site grows, you
can extend your alarm monitoring
capabilities by adding NetGuardian
DX Expansion units. Each
NetGuardian DX adds 48 more alarm
points, and you can daisy-chain up to
three NetGuardian DXs off each
NetGuardian 832A base unit.
Unit Capacity
Base NG 832 32
1 DX 80
2 DX 128
3 DX 176
NetGuardian DX: Expand your alarm monitoring
capacity with NetGuardian DX
Expansion Units.

Workshop ------New Section of Digital Family

Home Work:

Section 1: What is SCADA, and

what can it do for you?

SCADA is not a specific technology, but a type of

application. SCADA stands for Supervisory Control
and Data Acquisition — any application 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/machinery you want to monitor
a 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:
• Electric power generation, transmission and
distribution: Electric utilities use SCADA sys-

3tems to detect current flow and line voltage, to
monitor the operation of circuit breakers, and to
take sections of the power grid online or offline.
• Water and sewage: State and municipal water
utilities use SCADA to monitor and regulate water
flow, reservoir levels, pipe pressure and other factors.
• Buildings, facilities and environments: Facility
managers use SCADA to control HVAC, refrigeration
units, lighting and entry systems.
• Manufacturing: SCADA systems manage parts
inventories for just-in-time manufacturing, regulate
industrial automation and robots, and monitor
process and quality control.
• Mass transit: Transit authorities use SCADA to
regulate electricity to subways, trams and trolley
buses; to automate traffic signals for rail systems;
to track and locate trains and buses; and to control
railroad crossing gates.
• Traffic signals: SCADA regulates traffic lights,
controls traffic flow and detects out-of-order signals.
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
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:
• Does your equipment need an uninterrupted power supply
and/or a controlled temperature and humidity environment?
• Do you need to know — in real time — the status of many different
components and devices in a large complex system?
• Do you need to measure how changing inputs affect the output
of your operations?
• What equipment do you need to control, in real time, from a
distance?
• Where are you lacking accurate, real-time data about key
processes that affect your operations?
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 can you 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:
• Access quantitative measurements of important processes,
both immediately and over time
• Detect and correct problems as soon as they begin
• Measure trends over time
• Discover and eliminate bottlenecks and inefficiencies
• Control larger and more complex processes with a smaller, less
SCADA Tutorial • DPS Telecom • 4955 East Yale Avenue, Fresno, CA 93727 • (800) 622-3314 • Fax (559) 454-1688 • www.dpstelecom.com
4
Learn SCADA the Easy Way: Attend DPS Telecom Factory Training
Learn SCADA in-depth in a totally practical hands-on class. The DPS Telecom Factory Training Event will show
you how to make your alarm monitoring easier and more effective. You’ll learn basic SCADA functionality,
Derived Alarms and Controls, and how to configure automatic email and pager notifications. DPS training is the
easiest way to learn SCADA, taught by technicians who have installed hundreds of successful monitoring and
control deployments
For dates and registration information, call 1-800-693-3314 today or go to www.dpstelecom.com/training.
How DPS Telecom Can
Help You
Building the right SCADA system for
your business isn’t simple. It’s easy to
spend more than you need … but there
are also opportunities to save money
and improve operational efficiency that
you don’t want to miss. It’s hard to
learn everything you need to know and
still do your everyday job.
DPS Telecom can help you plan your
SCADA implementation, with expert
consultation, training and information
resources. DPS telemetry equipment is
built with the capabilities you need.
And DPS is committed to helping you
get the best SCADA system for your
specific needs.
DPS Telecom Guarantees
Success — or Your Money Back
You’re never taking any risk when you
work with DPS Telecom. Your DPS
SCADA system is backed by a 30-day,
no-risk, money-back guarantee. Test
your new system at your site for 30
days. If you’re dissatisfied for any reason,
just send it back for a full refund.
We don’t want your money unless
you’re completely satisfied. It’s that
simple.
specialized staff.
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 SCADA 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.