We completed a quick-turn project to provide a controller and HMI for a vacuum oven used by a large international manufacturer. The oven is a follow-on order to an existing system delivered over 4 years ago. This first oven used proprietary software that is no longer available, so a fresh start was needed. To keep the hardware cost to an absolute minimum, while ensuring that the Malachite code would be usable and upgradeable four years in the future, we chose an unusual platform: Codesys on Raspberry Pi.
Codesys is fully IEC 61131-3 compliant and is itself the core for most PLC manufacturers today. Although the Pi plus breakout boards were less than $300, the solution is feature-complete including: real-time charting, user access control, recipe storage, and data logging to a csv file. All of that displayed on a touchscreen plus all the logic needed to keep the machine stateful and running safely on the Pi.
Although most of our work remains with traditional PC and PLC based systems, running Codesys on a Pi with a UniPi breakout board is just one example of the hobbyist-industrial convergence that has been occurring for the past few years. It’s a fast-to-code, super low-cost solution that is appropriate when the number of inputs are low, hard real-time is not required, and a separate safety system is not needed.
Both Malachite and our customer are pleased with the results of this experiment. Codesys on Raspberry Pi opens many opportunities to apply a modern standards-compliant text-based language (not ladder diagrams) to control new or existing industrial systems.