The source driver module has been ordered and assembled. Tomorrow I plan to do the first tests with it and see how well it works. I assembled some small USB-dongles that I ordered PCBs for as well which seem to work. With those I can hook a computer up to the control bus and use the computer just as an openASC device which is perfect for operating a whole station remote.
The driver modules have 20 outputs which pair wise can source up to 2A (drivers handle 4A but fused with polyswitches at 2A) so you can run 2A with one output or 1A on two outputs. No configuration of the driver board is needed, all that you do is set the offset address with a DIP switch.
The communication bus uses the same principle as old coax ethernet. You terminate each end of the bus with a 50 ohm termination and it drives 120mA into the bus which gives a very good looking signal which handles interference very well. This will be tested hopefully this summer in a real contest enviroment.
Here are some pictures of the source driver: