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Reserve Your Seat TodayLearning from real-world examples is always easier than dry, textbook-style information. I'm increasingly a fan of teaching SCADA concepts using actual bid documents.
For today's lesson, I've found a bid document online. I will leave it anonymous since what's important is the handful of snippets I've extracted to guide our discussion.
Let's get started!
The SCADA bid document specifies: "The SCADA system software shall support a client/server system architecture."
This means the system should be organized so that a central server communicates and supplies services to multiple client devices. This is foundational in SCADA systems. It ensures centralized control and distribution of tasks.
As you probably also recognize, this architecture is hardly unique to SCADA. The client/server model is in play on every webpage on the internet, including this one.
You get a real-world example of a "server" with DPS Telecom's T/Mon. T/Mon is the central hub (an "HMI" in SCADA terms), managing and relaying information between humans and your indivuals agents/PLCs/RTUs. T/Mon's design ensures that monitoring and management happen seamlessly, bridging gaps in communication and offering you an intuitive interface to manage your network alarms.
The bid further mentions, "Each operator workstation application software shall be designed to optimize performance and minimize network traffic by maintaining a local database on each workstation that adaptively updates only the value of data points that are currently being displayed on that workstation."
Simply, this demands that each workstation be data-efficient, only updating what is immediately relevant. There's always a balance to be struck between data currency and bandwidth efficiency. This bid document describes one fairly explicitly (although not down to specific bandwidth limits).
NetGuardian, the family of RTUs from DPS, ties into this principle. Its primary function as a Remote Terminal Unit (RTU) is to monitor potential threats and activities, but it does so efficiently. Like any quality RTU, every NetGuardian is engineered to relay vital information, ensuring the network isn't flooded with redundant data. When operating with a T/Mon master station, we use an efficient protocol (DCPx) to further reduce what would otherwise be a verbose SNMP trap or DNP message.
Regarding communication, the document states: "The communication server software shall support multiple gateway/RTU protocols (serial and TCP/IP based)... As a minimum, communication software licenses shall be furnished to support the following remote device protocols: DNP 3.0, and QUICS scan task."
This spec points to the versatility and adaptability required of SCADA systems. They must communicate in various languages or "protocols". If two devices don't support a common protocol, they can't communicate.
Both NetGuardians and especially T/Mon support this requirement. NetGuardian, though primarily an RTU, possesses the potential to understand and communicate using a variety of protocols. Recent "G6" models can accept MODBUS and SNMP as local inputs.
T/Mon, as a central master station, supports dozens of different protocols. These include various open standards and some proprietary/legacy protocols specific to one manufacturer or used in an older era. T/Mon's adaptability ensures that, irrespective of the protocol a device uses, you can bring it under your monitoring umbrella.
The desire to have a single, cohesive SCADA system is hardly unique. In decades past, you could get "trapped" with one manufacturer's system and have no easy way to migrate or add third-party equipment.
In the next section, the bid emphasizes interfacing: "The SCADA Master Station shall incorporate an 'open system' architecture with demonstrated interoperability with other hardware and software platforms."
This calls for the system to be self-sufficient and effectively communicate with external systems, making it a part of a more extensive, integrated network.
We really built the T/Mon product primarily on this philosophy. It's something like a "universal adapter".
T/Mon can integrate and communicate with a wide range of systems, ensuring the SCADA system remains cohesive and not disintegrated (with multiple systems requiring multiple operators).
Diving deeper into this SCADA bid document, there's a key focus on "Internet Web Reports for Live SCADA System Data". Specifically, the bid states: "The Contractor shall quote a secure Web Report facility which displays live SCADA data on user PCs connected to the network using a standard Internet Browser such as Internet Explorer or Mozilla Firefox."
What does this mean in plain English? The goal here is to ensure that your critical SCADA data isn't confined to specialized systems or locations. The data should be at your fingertips, anywhere and anytime.
This contrasts with earlier technology, which often revolved around installed software on specific PC workstations. That created IT/security headaches and frequently limited how many "seats" could be installed.
T/Mon has evolved over the years to match this industry standard. We've had a web interface for about 20 years now. The latest version is fast and not limited by seat count.
In this bid, there is also a broad range of required export formats: "It shall be possible to export Web reports in HTML, Excel, Web archive, Acrobat PDF file, TIFF file, CSV (comma delimited), and XML file formats."
The flexibility in exporting data ensures that the reports can be tailored for presentations, reviews, or in-depth analyses, making the data not just accessible but also usable.
Using T/Mon and NetGuardians as examples, you can export PDF history reports and CSV alarm history (opens in Excel or other spreadsheet software). Although image export is not directly supported, I have frequently seen my clients take screenshots of the T/Mon web interface to email coworkers.
Finally, let's look at the "SCADA System Security Features". The bid document states: "The proposed system shall be configured with dual redundant SCADA servers which are fully synchronized... The system shall be capable of using up to four servers for redundant SCADA database servers." This is a mandate for a robust safety net. The dual or quad server redundancy ensures that even if one server faces issues, the system won't falter, thanks to the backup servers.
T/Mon supports dual-redundant configurations for high-uptime scenarios (most DPS clients require high uptime for mission-critical telecom/power/safety operations). It also includes redundant drives.
Just as an RTU's job is to notify when all else at a remote site fails, the secondary redundant T/Mon silently steps in when the primary server goes down.
NetGuardian RTUs are telco-grade and generally have dual-redundant power supplies and fuses.
SCADA projects are complicated, especially if you haven't worked on one before. If you have questions after reading, I have answers for you.
For help with your SCADA project, just give me a call at 1-800-693-0351 or email me at sales@dpstele.com
Andrew Erickson
Andrew Erickson is an Application Engineer at DPS Telecom, a manufacturer of semi-custom remote alarm monitoring systems based in Fresno, California. Andrew brings more than 17 years of experience building site monitoring solutions, developing intuitive user interfaces and documentation, and opt...
