Xbee isn't bad, provided you have good signal strength. Before I started teaching I worked for an HVAC optimization company that automated fast food restaurant

Xbee isn't bad, provided you have good signal strength. Before I started teaching I worked for an HVAC optimization company that automated fast food restaurant chain air conditioning. It folded due to politics with the owners, but the product worked really well. One of our early adopters was actually a small Health Center. I've got some modbus scripts that were written in Python while we were working with one of our clients. Its nothing great, just a few read/write functions. If you want I'll send them to you.