I’ve recently been diving into integrating my HVAC system with OpenHAB using Modbus, and I must say, it’s been an enlightening journey! 
While setting up my Pluggit AP310 ventilation unit, I encountered a few hurdles, but each challenge brought a new learning opportunity. Here’s what I’ve discovered and how I navigated through the process.First, I wanted to read temperatures and control the fan speed. I started by configuring the Modbus binding, referencing the Pluggit documentation for register addresses. I set up holding registers for temperature readings and a separate register for fan speed control. The initial setup looked something like this:plaintexttcp.value01.connection=192.168.6.181:502tcp.value01.id=1tcp.value01.start=132tcp.value01.length=2tcp.value01.type=holdingtcp.value01.valuetype=uint32For the fan speed, I mapped the values to a switch in the sitemap, allowing me to adjust the settings remotely. However, I faced some issues with the connection timing out occasionally. After some research, I realized adjusting the poll interval and ensuring the device was on the same subnet helped stabilize the connection.One thing I’m still curious about is writing to registers to set fan speeds. I’m cautious about sending the wrong commands, so I’ve been testing with small adjustments first. I’d love to hear from more experienced users on best practices for Modbus writes without risking device damage.This project has not only improved my home’s ventilation system but also deepened my understanding of Modbus integration. It’s amazing how a bit of troubleshooting and persistence can turn a complex setup into a seamless part of your smart home ecosystem. 
If anyone has tips or success stories with Modbus HVAC integration, I’d love to hear them! Let’s continue to explore and share our experiences to make smart home automation even more accessible and efficient for everyone. 