CM19A is cheap and you must have a wireless transceiver module ie TM751, but i must admit investing in the CM15A was worth it, But CM19A will get you started.
In Windows if you use the AHP SDK you can use command prompt to send commands, the CM19A you would use (ahcmd.exe sendrf A1 on)
where as the CM15A you can use ( ahcmd.exe sendplc A1 on, or the above command ) there is also receive commands and more,
I'm not sure about the protocol but CM19A is only RF, if there is any test on windows i can run for you i will, I'm just useless at writing code