@Ray: Thanks for the explanation. I agree that zone re-ordering is preferable over re-mapping. I had not considered the complexities of 72 zones reordering. I was just imagining a way to change the order by drag and drop or repeatedly pushing an up- or down button in each zone-bar.
One way to simplify might be to change the program interface from a full list of all available zones to an ‘add zone to program’ option where you start with an empty program and add zones as you need them en then place them in de desired order.
And by the way. I was confused about the GPIO option in the advanced tab. I now realize it is only applicable in/on OSPI and the GPIO does NOT refer to the physical zone connectors on Open Sprinkler. My mistake.
Anyway, (FYI) I came to a work around using two programs and two dummy zones (nr 9 and 10). Zone 9 results in an advanced master start and zone 10 in delayed master stop.
Program one contains only zone 9 (activating Master 1 – the well pump via relay)
Program two starts 2 minutes after program one (activating master 1 again and also master 2 -the two NO/NC valves redirecting flow from the cistern to the irrigation system)
Program one runs for 3 minutes so there is an overlap of one minute in activating master 1 – because I noticed that the well pump relay will shut down momentarily when the programs are sequential- causing a power interruption to the pump for about one second (not desirable for a pump)
Program two will end with dummy zone 10 allowing for the irrigation solenoids to close under pressure and advanced shut down for master 2 to redirect flow from the irrigation system to the open cistern to avoid irrigation water entering the well as water flows back once the pump stops under pressure of about 200 feet of water column.
The advantage of this solution is twofold:
1) does not cost a physical zone (like zone nr 3 acting as a dummy when only one program is used)
2) still allows for automatic changes to the duration of program 2 (the irrigation program) because of weather forecasts or sensor input
Disadvantage is:
1) start times of the two programs must be coordinated and in tune with each other. So a change in start time for one program must be manually matched with a change of the other program’s start time. This becomes more of a challenge in more elaborate and complicated programming schemes
It is a workaround that takes a little thinking through and requires some user-alertness. Would improve a lot with zone re-ordering, making that a nice-to-have feature, not a need-to-have.
Thanks for elaborate reply, I hope my work-around may benefit other OS users or challenge someone to come up with (even;) better approaches. and btw: I am available for betatesting or brainstorming about zone re-ordering anytime.