It seemed to me I should use the NC contact between the sensor and the EZFlora, so that when the rain would trigger the sensor and open the contact Pin 6 voltage would be pulled up to +5V. (If I would use the NO contact pin 6 would be pulled down to ground on activation).
You are correct in the sense there is an alternative wiring scheme (connect between the common line going to all the valves and the EZFlora) that would not require any configuration and would always work. However using the sensor input would be preferable as it would be possible to know when it has been inhibited by rain.
I tried the command to enable the rain sensor as both Standard and Extended but neither seems to work. After sending this command is it written permanently in the memory or would I need to send it again if the unit is disconnected for any reason?