Elk Failsafe rules

[Hermanus]

What would qualify as a Failsafe rule to control sprinklers? I connected my solenoid valves to Elk and am very happy with how it works but is concern that if something goes wrong the sprinklers will stay open. My setup is as follows:

Hardware: Use Elk outputs to control relays that switch 24VAC to open and close valves (very simple, but so far very effective).

Software: Created a task (Water_Lawn) and 2 Custom Values (Start_Water and Watering_Time). Wrote the following rules:

WHENEVER TIME IS Watering_Time (Cust Set 1)
THEN ACTIVATE Water_Lawn (Task 3)

WHENEVER Water_Lawn (Task 3) IS ACTIVATED
THEN TURN Sprinkler Side (Out 8) On For Watering_Time (Cust Set 2)
THEN TURN Sprinkler Back (Out 9) On For Watering_Time (Cust Set 2)

(I initially thought 2 zone were required, but the water pressure is enough to pull both valves open at the same time)

Are these rules Failsafe? If not what do I need to change to make the Failsafe?

Thanks in advance.

 

[Spanky]

Write an "upon powerup/reset Rule" to put everything in a known state. The M1 turns everything off should the processor reset or power is restored.

I control the water refill on my outside fish pond with an output expander from the M1. I have also added additional Rules that only allow the water to run for a short period of time with each refill request. I have had my water level detector lock up requesting a refill from trash in the water. Every hour if the refill sensor is requesting water, I allow the water valve to turn on for 20 seconds. This keeps the pond level full and limits the water level overfilling if the sensor locks up. The water valve is a lawn sprinkler valve controlled from 24 VAC switched through a relay on a relay output expander off the M1.

This refill system has been working for about 3 years and works very well.

The water sensor is made with a 3/8" door/window reed switch and 1/2 inch plastic pipe from the local hardware store. I glued a piece of styrofoam to a moveable piece of pipe that held the magnet. When the magnet moved far enough away from the switch, the switch opening told the M1 to turn on the refill valve. The reed switch is totally sealed, so water does not affect it.

 

[Hermanus]

Do you mean resetting all outputs when power comes back up?

Also my ElkRP is acting funny. In the New Rule window there is no OK button anymore to submit the rule, nor is there a [X] in the title bar to close the window. I have to open Task Manager and close ElkRP there to get out of it.

On a different topic, Cocoontech keeps loging me out. It makes it very frustating to post comments, Dan any ideas.

 

[Steve]

I think the issue that has come up is what happens if there is comm lost between the irrigation valve and output/relay. Granted, imho it would be a rare failure requiring a cut wire or something, but if an irrigation valve was turned on on something happened to where the output/relay can't turn off, then the water runs forever. I think that's why BSR suggests using a Rain8 instead of M1/Relays because the Rain8 has a safety shutoff timer, although I think there are still alot of variables there. Like say the Rain8 completely locks up/loses its mind/fries, etc the safety timer would not work. These are the same issues the M1 would have, except for the case of of something happens to the wire or bus between the m1 and a remote relay board, which in my mind would be a very rare occurrence indeed.

The shutoff outputs on startup/reset are a good idea but would only cover a rare glitch of the M1 rebooting or something. I guess you can do some watchdog events or something using outputs. You can also look here at a few other ideas. It is a good idea to have an overall disable override as well.