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How to Implement a SCADA Network

Morgana Siggins
Morgana Siggins
Monitoring Specialist

SCADA network and control can save you a lot of money and increase profitability. However, your SCADA implementation (if not done properly) can be a sinkhole of cost overruns, delays, and limited capabilities.

Let's go over some of the essentials of SCADA network technology and the main guidelines for evaluating SCADA systems. This way you can implement a SCADA network that best fits your needs.

Before Anything Else: What Exactly is a SCADA Network and What Can it Do for You?

The SCADA meaning in the engineering of networks is not related to a specific technology, but to a type of application.

Supervisory Control and Data Acquisition (SCADA) is a computer system that gets real-time data about a system in order to control that system is a SCADA application.

A SCADA network has two main elements:

  1. The process/system/machinery you want to monitor and control
    This can be a power plant, a water system, a network, oil and gas, a system of traffic lights, or pretty much any other critical infrastructure.
  2. A network of intelligent devices that interfaces with the first system through sensors and control output
    This network, which is the SCADA system, gives you the ability to measure and control specific elements of the first system.

Where Can You use a SCADA Network?

You can use SCADA to manage any kind of gear.

Normally, 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 individuals can comfortably deal with.

Here are some of the examples of where SCADA networks can be implemented:

  • Electric power generation, transmission and distribution
    Electric utilities use SCADA systems to detect current flow and line voltage, to monitor the operation of circuit breakers, and to take sections of the power grid online and 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 network 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 also can be used to regulate traffic lights, to control traffic flow and to detect out-of-order signals.
SCADA networks
SCADA networks are used in many different industrial plants, such as water/sewage, power, manufacturing and mass transit.

This list barely covers all the possible applications for SCADA systems.

SCADA networks are used in nearly every industry and public infrastructure project - simply anywhere automation increases efficiency.

Also, these examples don't really cover how deep and complex SCADA data can be. In every industry, managers need process data and control multiple factors and the interactions between those factors. SCADA systems provide the capabilities and the computational power to track everything that's important to your operations.

What is the Value of SCADA Networks to You?

Do you work in one of the previous fields listed?

Maybe you don't, but think about your operations and all the aspects that can affect your bottom line.

  • 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 statues of many different components and devices in a large complex system?
  • Do you have to measure how changing inputs affect the output of your operations?
  • What equipment you must control, in real time, remotely?
  • Are you lacking accurate, live data about vital processes that affect your operations?

Now, How SCADA Systems Work?

SCADA network systems are normally constituted of four components:

  1. Sensors
    Sensors - either digital or analog - and control relays that directly interface with the managed system.
  2. Remote terminal unit (RTU)
    These are small computerized units deployed in the field at specific remote sites and locations. RTUs serve as local collection points for gathering reports from sensors and field devices and delivering commands to control relays.
  3. SCADA master unit or human-machine interface (HMI)
    These are larger computer consoles that serve as the central processor for the SCADA network. The HMI software provide a human interface to the system and automatically regulates the managed system in response to sensor inputs.
  4. Communications network
    The communications protocol network connects the SCADA master unit to the RTUs in the field.
SCADA system
The process of communication over a SCADA system involves several different SCADA system components. These include the sensors and control relays, RTUs, master units, and the overall network.

The previous SCADA components perform the following SCADA network functions:

1. Data acquisition

First, a real-life SCADA network typically needs to monitor hundreds or even thousands of sensors. Some sensors measure inputs into the system - water flowing into a reservoir for example - 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). In real life, are used to measure simple states, such as whether the 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.

Analog inputs
Analog inputs provide continuous "how much?" data, unlike binary/discrete inputs that only have 2 possible states. Web interface gauge clusters make monitoring analogs more intuitive for you and your team.

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. So, if the temperature goes above or below this range, it'll trigger a threshold alarm. In more advanced systems, there are four thresholds alarms for analog sensors, defining Major Under, Minor Under, Minor Over and Major Over alarms.

2. Networked data communication

It's important 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.

SCADA networks 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 use 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 an 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.

3. Data presentation

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

The SCADA master station has multiple functions. It 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 then presents a comprehensive view of the entire managed system, and gives 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.

SCADA HMI
A SCADA HMI, also referred to as a SCADA Master, can provide a number of helpful extensions for network alarm management. RTU data can be filtered, analyzed, and monitored against operational standards. Out-of-range data can generate alerts to operators or maintenance personnel as required.

4. Process Control

If you have a sufficiently modern master unit, your SCADA network system can completely regulate all kinds of industrial processes automatically (without any human intervention). But, of course, you can still manually override the automatic controls from the master station.

So, 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 network can adjust the managed system in response to multiple inputs.

Controlling remote equipment
Controlling remote equipment from your operations center saves you expensive windshield time, and allows you to respond instantly to on-site problems. In this application, the system operator can send control commands from your Network Operations Center (NOC) to the on-site SNMP remote. You can even set up certain controls to operate automatically when certain alarm conditions occur.

How Can You Evaluate SCADA Systems?

Now that you know what SCADA can do for you, how do you make sure that you're really getting its full benefits?

Evaluating complex systems can be tricky - especially if you have to learn a new technology while still doing your everyday job. However, you've got to be able to make an informed decision, because the stakes are incredibly high.

A SCADA network 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.

  • You can spend a fortune on unnecessary costs.
  • Even after going way over your budget, you can still end up with a system that doesn't really meet all your needs.
  • Or, just as bad, you can end up with an inflexible system that just meets your present needs, but can't easily expand as your requirements grow.

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

What You Should Look For in Your 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:

  • Sufficient capacity to support the equipment at your site.
    But, no more capacity than you actually will use. At every site, you want an RTU that can support your expected growth over a reasonable period of time. But it's simply wasteful to spend your budget on excess capacity that you won't use.
  • Rugged construction and ability to withstand extremes of temperature and humidity.

    You know how hard on equipment your remote locations can be. Keep in mind that your SCADA network needs to be the most reliable element in your facility.

  • Secure, redundant power supply.
    You need your SCADA network up and running 24/7, no excuses. Your RTU should support battery power, and - ideally - two power inputs.
  • Redundant communication ports.
    Network connectivity is as important to SCADA operations as a power supply. A secondary serial port or internal modem will keep your RTU online even if the LAN fails. Plus, RTUs with multiple communication ports easily support a LAN migration strategy.
  • Nonvolatile memory (NVRAM) for storing software and/or firmware.
    NVRAM retains data even when power is lost. New firmware can be easily downloaded to NVRAM storage, often over LAN - so you can keep your RTU's capabilities up to date without excessive site visits.
  • Intelligent control.
    As I noted before, modern SCADA remotes can control local systems by themselves according to programmed responses to sensor inputs. This isn't necessary for every application, but it does come in handy for some users.
  • Real-time clock for accurate date/time stamping of reports.
  • Watchdog timer to ensure that the RTU restarts after a power failure.

What You Should Look For in Your SCADA Master

Your SCADA master should display information in the most useful ways to human operators and intelligently regulate your managed systems. The following is a checklist of SCADA master must-haves:

  • Flexible, programmable response to sensor inputs
    Look for a system that provides easy tools for programming soft alarms (reports complex events that track combinations of sensor inputs and data/time statements) and soft controls (programmed control responses to sensor inputs).
  • 24/7, automatic SMS or email notifications
    There's no need to pay personnel to watch a board 24 hours a day. If equipment needs human attention, the SCADA master can automatically send an email or SMS directly to repair technicians.
  • Detailed information display
    Your system should display reports in plain English, with a complete description of what activity is happening and how you can manage it.
T/Mon alarm system
When an alarm occurs, an HMI like the T/Mon alarm system, presents the data in a form that is usable by the human network operator.
  • Nuisance alarm filtering
    Nuisance alarm desensitize your staff to alarm reports, and they start to believe that all alarms are nonessential alarms. Eventually they might stop responding even to critical alarms. Look for a SCADA master that includes tools to filter out nuisance alarms.
  • Expansion capability
    A SCADA network is a long term investment that will last for as long as 10 to 15 years. So, you need to make sure it will support your future growth for up to 15 years.
  • Redundant, geo-diverse backup
    The best SCADA systems support multiple backup masters, in separate locations. If the primary SCADA master fails, a second maser on the network automatically takes over, with no interruption of monitoring and control functions.
Network reliability
Network reliability can be further improved by utilizing alternate reporting paths and redundant power supplies.
  • Support for multiple protocols and equipment

    Early SCADA systems were built on closed, proprietary protocols. Single-vendor solutions aren't a great idea - vendors sometimes drop support for their products or even just go out of business. Support for multiple open protocols safeguards your SCADA network against unplanned obsolescence.

We Can Help You on Your SCADA Network Implementation

Building the right SCADA system for your business isn't that simple. It's easy to spend more than what you really need. However, there are also many opportunities to save money and improve operational efficiency that you don't want to miss.

It's also hard to learn everything you need to know and still make sure you're focusing on your daily job.

We can help you plan your SCADA implementation, with expert consultation, training, and information resources. Our equipment is built with the capabilities you need, and don't forget that we're committed to helping you get the best SCADA system for your specific needs.

There's no risk when you decide to work with us. Your SCADA network is backed by our 30-day, no-risk, and money-back guarantee.

So, you can 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 it's your perfect-fit solution. It's that simple.

Contact us today and let's dive into your SCADA implementation together.

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