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How to Implement a SCADA Equipment Network

Morgana Siggins
Morgana Siggins
Monitoring Specialist

A supervisory system 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:

Where is SCADA used
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.

You can find SCADA system projects in many different industries and public infrastructure - 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.

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) SCADA
    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
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 threshold alarms for analog sensors. These thresholds define 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 machine that reports to human operators over a specialized computer 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 send a command to 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 you know what SCADA can do for you. But, do you know how to get 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.

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 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 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:

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.
Network reliability
Network reliability can be further improved by utilizing alternate reporting paths and redundant power supplies.

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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