I am presently looking at the open sprinkler to replace my current one and have difficulty determining how the rain gauge sensor is used by the firmware and whether it can be used to take into account evaporation as well as rain.
As a background I incorporated a rain sensor in an old unit I have and used the sprinklers to water the rain gauge, the sprinklers were set to water every day and sense the rain gauge, the next cycle was activated after a few days when evaporation had taken effect, if it also rained in the mean time the evaporation was effectively negated. The only catch was that irrigation stopped as soon as rain (or being sprinkled) was detected, effectively turning off the last station early. I had to rig up a method of disconnecting the rain gauge during the last cycle that wet it whilst the valve was open so the watering did not turn itself off.
1. If it rains during a period that watering is underway, does this turn the watering off or is it only checked at the start of the cycle time?
This system worked very well in the hot dry summer days, achieving daily watering when very hot and reducing to every 2-3 days when cooler but still no rain. Rain would also reduce the frequency of watering as well depending on the quantity.