Exploring Open-Source Hardware from an Industrial Control and Automation Perspective

How long does it take to grow a technical workforce?

How long does it take to grow an experienced control technician or the electrical / mechanical engineer capable of designing, modifying, and repairing industrial control and automation systems?

Can it be done in a decade?

Can we accelerate the learning experience using the tool and techniques commonly associated with the open-source communities?

This brief explores the intersection of traditional open-source hardware initiatives framed within the context of industrial control and automation. We show that there is overlap with emerging technologies that blend the fields together. Programmable Logic Controllers (PLCs) based on a Raspberry Pi and an Arduino foundation such as shown in Figure 1 are good case studies. Devices like these are at the center of open software and open hardware initiatives.

The crossover becomes even more interesting when we consider workforce limitations and the demanding and extensive education required for electrical and mechanical technicians, assemblers, and engineers. As a call to action, the open-source community has the potential to reduce the time it takes to grow an experienced workforce.

What is open-source hardware?

Open-source hardware share a common definition with open-source software. As a general principle, open products are designed so that anyone may study, change, adapt, and then redistribute the product. The concepts are generally framed within large supportive communities enabled by free and open worldwide communication using our global networks.

The open-source software is generally concerned with computer code while open-source hardware is more complex. However, we could argue that modern hardware designs often include software to operate the PLC. Other materials describing the physical attributes are also required including wire diagrams, PCB files, CAD drawing, and physical placement of fields devices such as sensors and actuators. This may also extend to a physical description and a set of design files for the machine or process being controlled.

At its core, the open-source initiatives are concerned with the rights of the user. We could also argue that these rights are closely related to education as the action verbs of study, change, and adapt are key elements of any education.

Figure 1: PLCs such as the Kunbus Revolution pi and Opta provide a bridge between the open-software and open-hardware domains.

What devices are traditionally considered part of the open-source hardware movement?

One answer may be found by examining projects that have been certified by the Open Source Hardware Association. According to a recent State of Open Source Hardware statement, the field is primarily dominated by electronic and 3D printing. This is not a surprising especially for DigiKey readers who are familiar with the Arduino community using devices such as the Arduino Uno and derivatives such as the Sparkfun Pro Mini as pictured in Figure 2. Products such as these have been the engine of many community-based open source initiatives. This observation is further supported by visiting places such as Instructableas where we can find many electronics project, 3D printing, laser cutting, and combinations of all three. Another example is the DigiKey hosted Maker.IO platform. The recent welcome page is included as Figure 3. The featured Raspberry pi vs Arduino links perfectly align with our discussion.

Figure 2: Picture of the Arduino UNO and the Sparkfun Pro Mini as two widely recognized devices found at the core of many open-hardware initiatives. Also, devices such as this are at the core of many educational open-source initiatives.

Crossover from the open-source software initiatives

As implied above, Arduino and Raspberry Pi are two well-known names in the makerspace and open-software communities. It’s no surprise that industrial controllers from both communities are available. In Figure 1 we see the representative Kunbus Revolution Pi and the Arduino Opta Programmable Logic Controllers (PLCs). Internally the Kunbus PLC uses a Pi compute module and the Arduino uses an embedded processor that appears to shares hardware with the Arduino H7 PORTENTA Pro.

Figure 3: Feature page of DigiKey Maker.IO captured April 26, 2024. Note the Arduino vs Raspberry Pi article.

What constitutes pure open-source hardware design?

Let’s take a moment to recognize that there are shades of gray with regards to open-hardware. For example, we could argue that Raspberry Pi is not pure open source as we do not have access to the internal compute module schematics. However, Kunbus does provide schematic for the RevPi PLC. Likewise, Arduino provides schematics for related device such as the PORTENTA Pro H7 but not for the Opta PLC itself.

A challenging open-source hardware project would be to combine the two PLC devices. For example, from a purely hardware perspective, we could produce a new device featuring the interface circuitry of the RevPi and an Arduino H7 brain.

Why aren’t all devices open-source?

From a purist standpoint, it would be nice if we had full access to all the documents and procedures associated with a particular product. At the same time, we should recognize that there are reasons to keep the complete recipe hidden. Like the Kunbus and Arduino example, there are limitations. I’ll leave it to you to debate patents, trade secret, and the return on investment for capital intensive projects.

Big components vs little components

There is a temptation to think about open-source hardware in terms of resistors, transistors, microcontrollers. An excellent example is the Arduino Mega. At one point the Mega was included as a reference design in the Eagle CAD software. This was wonderful from an education standpoint as students could explore multiple aspects of the design. As an example, I once gave an assignment to calculate the size of the heatsink associated with the Mega’s power supply. This included the thermals to transfer heat from one side of the board to the other.

We should view industrial open-hardware ideas at a higher level

Industrial controls should not be viewed at the component level. Instead of exploring regulators, MOSFETs, optocoupler, and microcontroller, we should focus on wire diagrams, user interface components, and module level assemblies such as the PLC and motor drives.

Equally important are the algorithms that describe how a machine or industrial process is monitored and controlled. This is yet another recognition that open-source hardware is inseparable from open-source software. Exploring the ladder logic program for a PLC is just as important as exploring the C++ or python source code.

This thought captures the beating heart of open-source hardware initiatives for industrial controls. It is at this level that each person is free to study, change, adapt products to new situations. There are thousands of hardware combinations for any given project. At the same time there is more than one way to perform a task. A machine of control process may be improved by changing the type of sensor, the control algorithm, or the various machine hardware and actuators.

What is the state of open-source initiatives for industrial control and automation?

We should recognize that industrial controls are built to withstand harsh environments with less-than-gentle operators. These robust components are associated with a higher cost thereby placing the point of entry out of reach for many would be experimenters. Along those same lines, industrial controls are used for time and money sensitive industrial processes. We know that equipment reliability directly affects the bottom line of a company as down time can cost hundreds to thousands of dollars per minute. Stated another way, there is little time or money for experimentation.

Safety is another consideration. Inexperienced or inattentive developers can create dangerous conditions. As a simple example, consider a machine with a light curtain. Obviously, the machine will stop when the curtain is broken. However, we need to carefully consider how the machine will restart. We must consider how the human will interact with the machine to clear jams or partially completed work assembles. A simple mistake could damage the machine, injure, or even kill a person.

However, that is not the end of the story.

There is a good argument to focus industrial open-hardware initiative to the classroom setting. Alternatively, there is something to be said for the long tradition of mentoring. This is recognition that classroom experience will not make you an expert. Instead as part of your decades long learning experience you can build machinery and industrial controls under the supervision of a mentor. This coupled with a community of open-source software and hardware can lead to better results than going it alone.

Will workforce pressures expand open-source initiatives?

It’s difficult to predict the future. Yet, we can take an honest look at our present situation and speculate about how thing will change. When we look at industrial automation, we see a few trends:

  • The complexity of technology is increasing. Part of this is enabled by increased computation power. This is part if Industry 4.0 where enables vision recognition and even advanced AI capabilities. Along these same lines, there is increased complexity in the control algorithms.

  • There is a trend for increased networking along with the complexities and hazards of cyber security. This falls under the umbrella of Industry 4.0 where remote control and monitoring are used to increase internal efficiency (measured by time and energy consumption) and optimize the plant’s integration into larger logistics chains.

  • There are increasing pressures to expand automation to perform tasks previously completed by humans.

We could certainly expand this list, but it’s safe to say industrial controls and automation is a growing sector. At the same time, we need to recognize that it takes great effort to grow skilled technicians and engineers. In the past, we may have been content when students learned about relays and ladder logic. Somehow that seems incomplete given our optimist list of increased system complexity with its expanded cyber component.

Perhaps this is where we most need an open-hardware initiative. The open-source community could truly help guide and prepare future technician and engineers. Those community reference designs, and case studies would be of tremendous value to potentially reducing the time it takes to grow our future workforce.

Parting thoughts

Before we close, we should reflect on the challenges and opportunities of open-source initiatives especially when we include manufacturing. The association with education is perhaps the most important aspect especially when we recognize the time and dedication it takes to grow a competent workforce. The core open-source concepts of study, change, and adapt when applied to industrial control and automation could have a positive benefit. They have the potential to reduce study time while simultaneously opening students to the full potential of modern controls and techniques.

I trust that this brief has effectively framed future debates that encompass the professional community of enthusiasts and educators. At the same time, I’ll freely admit that this brief barely scratches the surface of a highly complex topic. Please share your ideas and links to your contributions to open-source hardware projects. Your work may help shorten the decades long training of future technician and engineers.

Best Wishes,


Return to the Industrial Control and Automation Index.

About the Author

Aaron Dahlen, LCDR USCG (Ret.), serves as an application engineer at DigiKey. He has a unique electronics and automation foundation built over a 27-year military career as a technician and engineer which was further enhanced by 12 years of teaching (interwoven). With an MSEE degree from Minnesota State University, Mankato, Dahlen has taught in an ABET accredited EE program, served as the program coordinator for an EET program, and taught component-level repair to military electronics technicians. Dahlen has returned to his Northern Minnesota home and thoroughly enjoys researching and writing articles such as this. LinkedIn | Aaron Dahlen - Application Engineer - DigiKey

1 Like