We once reversed engineered Schneider Electric's ION protocol because they wanted to charge us $10k per "seat" to get software that could interact with it directly. We took home a controller and developed a Python program that could intercept and understand the RS-232 comms. We then developed our own system to interact with it. It was all unencrypted. I just did a quick search and it looks like "Secure ION" is now a thing, introduced in the year 2023. Which just proves my point.