The Raspberry Pi Isn’t a PLC
The Raspberry Pi shows up everywhere in control and data acquisition discussions. Sometimes it’s presented as a low-cost alternative to industrial hardware. Other times it’s dismissed outright as something that doesn’t belong anywhere near a real system. Both reactions come from the same place: evaluating it against the wrong expectations.
The Raspberry Pi isn’t a PLC. Treating it like one is where many projects go to die.
People tend to do one of two things: they either try to use it like a PLC, or dismiss it because it isn’t one. Both approaches miss the point.
The problem is not the hardware. It’s how the system is being framed.
Not all control problems are deterministic. Designing every system as if they are leads to unnecessary complexity. Most systems don’t fail because of control loops. They fail because of everything around them.
This is where the distinction becomes important.
The Raspberry Pi isn’t a PLC. It’s a system-level platform and should be treated as one.
Some control problems do require tightly bounded timing and deterministic execution. But most do not. Yet many systems are still designed as if they do, and that assumption drives unnecessary constraints into the architecture.
In practice, the Raspberry Pi is more capable than it is often given credit for. I’ve successfully used a Raspberry Pi as a quad PID controller. The difference wasn’t the hardware. It was how the system was designed.
Millisecond-level control loops are well within reach when the system is structured appropriately. The limitation is rarely the platform. It’s the expectations placed on it.
Where the Raspberry Pi Fits
Where the Raspberry Pi truly stands out is not just in control, but in everything around it.
It provides a flexible foundation for integrating devices and protocols, managing network communication, aggregating and logging data, and building user interfaces and dashboards. It supports rapid development and iteration, allowing systems to evolve quickly without being locked into rigid architectures.
In many real-world systems, these responsibilities are fragmented across multiple tools, layers of middleware, and custom scripts. The Raspberry Pi allows them to be consolidated into a single, cohesive platform.
That said, using the Raspberry Pi for data acquisition and control typically involves external interface hardware. Analog inputs, outputs, and signal conditioning are handled through peripheral devices connected over I²C, SPI, or other interfaces.
This isn’t a limitation. It’s how flexible, modular systems are built. Separating the compute platform from the I/O layer allows the system to scale, adapt, and evolve without being constrained by fixed hardware capabilities.
The Real Issue
The real issue isn’t whether the Raspberry Pi can be used in control systems.
The issue is where it is placed.
The mistake isn’t using the Raspberry Pi. The mistake is assigning it the wrong role. When it’s expected to behave like a PLC, it’s evaluated against requirements it was never designed to meet.
Used correctly, the Raspberry Pi becomes the layer that connects everything else.
It can coordinate PLCs, PID controllers, and DAQ hardware. It can manage sequencing and test execution, aggregate and contextualize data, and provide system-level visibility. It can handle compute-intensive tasks, serve web-based interfaces, and manage network communication across the system.
In that role, it is not replacing dedicated controllers. It is making them part of a larger, coherent system.
Conclusion
The problem isn’t the Raspberry Pi.
It’s where people try to put it in the system.
If you’re building systems like this, I’ve been working on a platform that approaches the problem from this exact angle: SigCore UC