These firmwares configure Arduino Uno/Mega as Modbus input/output boards (RTU, no ASCII). This is especially useful for teaching purposes, as it provides hardware compatible with commercial PLC programming solutions such as CoDeSys at a low cost.
This project uses the excellent work of epsilonrt for all things Modbus protocol related by providing a device that is easy to use and allows the student to abstract from low level work and focus on automation design and implementation.
I use CoDeSys in my automation classes because it currently provides a modern software solution free of charge, it is compatible with a vast number of PCLs/brands, and supports the IEC-61131 standard, which makes it especially useful for teaching the basics of automation at the undergraduate level.
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