I was hoping for something a bit more automatic such as being able to set zones 1 and 4 to run with master valve 1 and zones 2, 3, and 5 from master valve 2. I currently do that with a standard sprinkler controller by using diodes to all zones used with master 2 and building triac outputs for master 1 and master 2. If master from main controller is on and no signal from diode circuit I enable master 1 output. If master from main controller is on and there is signal from diode circuit I enable master 2 output. I could use the same circuitry with opensprinkler but it would be great if it could handle this case in software so the master selection could be reprogrammed.