Necessity is the Mother of desperation.
Thanks for the link! - I'm looking forward to checking out the SDK. I'm currently using a SmartHome branded PowerLinc serial interface, but I sense that the CM15 is where its at now (although I'd need a price under $100 before I'd do the jump). So the code I have operates using a serial port ( Windows CreateFile/ReadFile/WriteFile ), and would probably only be of use to someone with this box.
I'd be most interested to find out if the send/receive rates are higher using the CM15 because if I implement a 'fastest possible' dimmer ramp its pretty slow on this PLC. I'm guessing it might be at the hardware timing level (as I understand it packets are sent near the zero crossing of the 60Hz signal, right?) even with a theoretical bandwidth as low as 9.6kbps. I have not investigated potential differences in here so perhaps someone has already done a comparison.