The industrial automation space is filled with acronyms and keeping track of the different variations and meanings can be a full-time job. In our industry, especially with our manufacturing and industrial automation customers, two of the most used acronyms are HMI and SCADA.

HMI = Human Machine Interface SCADA = Supervisory Control And Data Acquisition

To take these two terms further, I am going to define Human Machine Interface and Supervisory Control and Data Acquisition and explain how the two components not only play a key role in many of our industrial automation projects but also improve our business and reduce our operating costs. Let's start with defining HMI.


In simple terms, an HMI is a digital interface for a mechanical system. This interface can be a laptop, tablet, phone, or more traditionally, an industrial or panel PC, and its main purpose is to control and monitor equipment. An everyday example of an HMI is your thermostat. You press the up and down arrows to raise or lower the temperature of your space. The thermostat sends an electrical signal to relay your request to your furnace. Once your furnace receives the messages, it starts (or stops) producing heat to meet the temperature set by the thermostat. An HMI displays the real-time information we are gathering from our equipment. In the thermostat example, the thermostat is displaying the temperature of our room.

The HMI is also the tool we use to communicate with, and subsequently control, our equipment. In addition to reading the current temperature, we are writing our request to change the temperature, prompting a series of actions to turn on the furnace by pressing the up and down arrows to change our temperature setpoint. Use cases for HMIs spread far beyond residential heating applications. Engineers use HMIs to interact with a wide spectrum of equipment across a variety of industries.

Example industries include manufacturing, building automation, utilities, and transportation. Applications in these industries are more involved than just a single thermostat controlling a furnace. We often need our HMIs to control multiple disparate systems from a single platform. This expanding scope requires an open system architecture where we can connect devices as we bring them online. The SCADA system is the platform that supports this intra-communication between our devices. I'll explain this in detail below.


A SCADA system is a software platform that connects and communicates with hardware components in an industrial application. The architecture has several key components and features. Let's explore each of these, one at a time.

1. Connectivity

“Connectivity” is a blanket term for how our SCADA system is communicating with our pumps, valves, sensors, and other pieces of equipment. This communication can be done over a physical wire connection or by utilizing a wireless technology. The devices communicate their status with our SCADA system (or, an intermediate controller – more on that later) using a protocol. A protocol is simply the “language” our devices speak. We must make sure our SCADA system can speak the same language as the devices. Luckily, industries have standardized themselves on several open protocols. Common protocols in industrial automation include OPC UA, BACnet, Modbus, EtherNet/IP, and SNMP. To stay current with technology, the SCADA system often needs to receive data from a database (e.g., Microsoft SQL Server, Oracle, MySQL) or through a Web API (e.g., REST or SOAP services).

2. Industrial Controller

I hinted at this in the ‘Connectivity’ section, but an industrial controller is just a specialized computer that is hardwired to read data or execute actions among the physical devices in our facility. Most of the time, we need an industrial controller to translate the electric signals from our devices to a protocol that our SCADA understands. This might sound like a vast oversimplification of the role of an industrial controller, which, to be fair, often has its own standalone logic to perform calculations, aggregate values, and carryout actions. But, for the purposes of this discussion, we want the controller to do its job and relay that information to our SCADA system.

3. HMI

Human machine interfaces had their own section at the beginning of the blog, so I will just summarize here. An HMI is a local or remote interface that is used to read and write information to the SCADA system. The interface can be a laptop, tablet, phone, or more traditionally an industrial PC.

4. Data Historian

To create a historical account of the information in our SCADA system, we need to store the real-time data coming from our devices to a data historian. A data historian is a software tool that logs real-time data in a time-series database. The underlying storage can happen in an off-the-shelf relational database – e.g., SQL Server, Oracle, MySQL – or in a proprietary flat file that the logging software creates. The historian gives our operators the ability to view trends of our process data and recognize patterns to identify issues that have occurred (or may be imminent) in our processes. Proper implementation of a data historian will help us shift our equipment maintenance from reactive to proactive.

5. Modular Architecture

In the HMI section at the beginning of the article, I mentioned the need for an open system architecture with our SCADA platform. An open system architecture is a platform that is hardware and protocol agnostic. An agnostic system has a flexible framework and configuration tools to accommodate our growing operation. As we increase the number of physical equipment in our project or the quantity of data we are collecting from existing equipment, we need to be able to plug the new pieces into our SCADA system. To plug the new pieces into the SCADA system, we need a living platform that is easy to update and grow with the changing needs of the business. Part of this is having multiple data connectivity options, which we mentioned above. We also need the flexibility to make real-time adjustments to our data model and its organization.

For example, if we acquire the building next door and need to integrate three additional manufacturing lines into the system, what is the best way to accomplish that? Each line might already have its own set of equipment and repository of information that we want to incorporate in the SCADA system. As we add the physical space to accommodate the new equipment, we need to add the virtual space to accommodate the new data. The other important feature of a modular architecture is disbursing the functions of the SCADA system across multiple servers.

For example, having a dedicated server for the data historian, a dedicated server for real-time data collection, and a dedicated server to host any clients connecting to the system. A client is a broad term for any user of the system. The distributed architecture reduces the computing requirements (i.e., vCPU and RAM) of any one server. It also gives us wiggle room at the beginning of a project. We do not necessarily have to nail all of our requirements down because we can always add an additional server if the SCADA system eventually outgrows its originally intended scope.

You said these things were going to save me money?

At this point you have either read the whole blog or skipped right to this section (and I would not blame you for doing so). When we evaluate any new technology, our Return on Investment (ROI) needs to be our priority. The Swedish Medical Center in Seattle saw this return on investment in the first year of installing ICONICS HMI SCADA software.

The Swedish Medical Center partnered with MacDonald-Miller to leverage ICONICS HMI SCADA as part of a Fault Detection and Diagnostics system deployment across three of their Washington campuses. Across the three campuses, totaling over 2.8 million square feet, the Swedish Medical Center saved $350,000 in energy costs. The energy savings came largely from the platform’s ability to monitor and correct malfunctioning equipment. The Swedish Medical center estimates that it saved an additional $75,000 in operating costs by proactively addressing equipment anomalies. Read the full story here.

Where to start?

Believe it or not, there is a whole world of software dedicated to Human Machine Interface (HMI) and Supervisory Control and Data Acquisition (SCADA). ICONICS has been a worldwide industry leader in no/low code HMI/SCADA software since 1986. And we are continually improving our solutions, so our customers can keep optimizing their processes to stay ahead of their competition.

We can help you with any questions you have regarding implementing HMI/SCADA in your own facility or plant. So, please contact us at and let us get you started on your path to improving your operational efficiency.