@tbowmo thanks for the info. So am I correct in saying I can manually set the address of each sensor node (and the "gateway" I suppose) and they will talk to each other? If this is the case, great! I can build out the Modbus part myself. Where can I find documents on what the sensor messages look like?

Also, has anyone successfully ran a gateway firmare on an Arduino Mega? (I like the extra UARTs)

Hello Everyone. I am new to MySensors but not to home automation or even automation in general. I have been in the building automation and process control industry for 20+ years. I have experience with DDC and PLC controls. I have deployed "controllers" from Iconics, Delta, KMC, and Induosft. We call them HMI's or Human Machine Interface. Before I moved 9 months ago, I had a system in my house that included some fully programmable Modbus thermostats/controllers, wireless sensors from Nathan Chantrell - tinyTX, and an Indusoft HMI. The sensors talked to a Arduino Mega gateway that converted all their data to Modbus that the front end read over RS485.

OK, now to my question! I would like to use the MySensors stuff because it seems more robust and has lots of great options like acting like a repeater. Question is can I use this system without having to use a special controller software? Can I setup a router that also acts as a Modbus slave? Has anyone done this?

Thanks!