control a 9 zone sprinkler system using 8 wires??

[wired-up]

My irrigation installer planned a 6 zone irrigation system. I ran a cat 5 cable from M1G to the garage for the controller (using elk relays and 24 v source in garage) I went to look at the wiring after he finished and found he ran 9 zones instead of 6. Short of combining zones (which may or may not work with pressure issues) can anyone think of a way to control the 9 zones using the M1 and a Cat 5 cable to the relays?
My assumption had been a wire for each zone for the positve with one wire for a common negative, which would have worked with cat 5 with one wire to spare.
(You really never can assume you have enough wire run, can you?)
David

 

[DavidL]

Easy answer is to use the current run wires as serial wires and put a Rain8Net out next to the solenoids in a weathertight box. Only need three conductors. You can then daisy chain as many Rain8Net boxes as you want.
You will also need 24V AC (wallwart) out to the Rain8Net first box. The daisy chain wiring carries the voltage to all other Rain8Net boxes that are cascaded.

EDIT. Ok, read again that you are using an ELK. So, use the current wiring as RS485 wires and put a relay expansion module out next to the solenoids.

 

[robertmee]

Easy answer is to use the current run wires as serial wires and put a Rain8Net out next to the solenoids in a weathertight box. Only need three conductors. You can then daisy chain as many Rain8Net boxes as you want.
You will also need 24V AC (wallwart) out to the Rain8Net first box. The daisy chain wiring carries the voltage to all other Rain8Net boxes that are cascaded.

EDIT. Ok, read again that you are using an ELK. So, use the current wiring as RS485 wires and put a relay expansion module out next to the solenoids.

I would agree that's the best solution. If YOU really want to use relays you could get creative and use a binary setup, but it would take lots of contacts on each relay (unless you broke them up into sets and then it would take 2 or 3x as many relays).

 

[wired-up]

Thanks for the quick responces, this forum is great.
I hadn't thought of using the cat 5 as database bus wiring. Since I need 9 relays, I guess I'll get an output expander that has 8 relays and 8 voltage outputs and use an additional relay wired to one of the voltage outputs. Still much cheaper than the $250 my irrigation guy wanted to charge me for a controller (+ $75 labor to hook up)
thanks again, David

 

[bphillips]

Thanks for the quick responces, this forum is great.
I hadn't thought of using the cat 5 as database bus wiring. Since I need 9 relays, I guess I'll get an output expander that has 8 relays and 8 voltage outputs and use an additional relay wired to one of the voltage outputs. Still much cheaper than the $250 my irrigation guy wanted to charge me for a controller (+ $75 labor to hook up)
thanks again, David

Suggestion: Instead of just adding 1 additional relay to one of the voltage outputs you might consider adding an ELK-M1RB (8 output relay board). This plugs into the voltage outputs on the output expander and you end up with a total of 16 relay outputs to work with. It's not that much more expensive than an individual relay.

The benefit? One of the extra relays can be used as a "Master Switch". Wire the 24V power through the master relay and then to each of the relay commons. When you write rules to turn on sprinkler zone(s) you also need to turn on the master. But, when you need to quickly stop any sprinkler zones you can do so by only turning off the master since it will kill the power source to the other relays.

Extra relays... Good!

 

[az1324]

If YOU really want to use relays you could get creative and use a binary setup, but it would take lots of contacts on each relay (unless you broke them up into sets and then it would take 2 or 3x as many relays).

You could do this with a relay matrix and only 6 SPST relays. 3^2=9

So using one 8 relay board you still have 2 extra relays.

 

[keepersg]

If YOU really want to use relays you could get creative and use a binary setup, but it would take lots of contacts on each relay (unless you broke them up into sets and then it would take 2 or 3x as many relays).

You could do this with a relay matrix and only 6 SPST relays. 3^2=9

That is a very nice and elegant solution--one expander board and you can still implement a master control.

 

[wired-up]

Wow! Now I like the idea of the 'relay matrix' but being an electrical novice, can someone explain (or draw out) how to wire what I am assumming is a branched tree of relays to make it work with 6 or seven relays?
David

 

[az1324]

Here's a quick drawing.

 

[wired-up]

Oh, I think the light has come on! (single relay in my brain)
So there are 3 relays on the one side of the AC line and 3 on the other.
To turn on the left upper valve in your diagram you switch relay 1 and 4, to do the lower right one you would switch relay 3 and 6.
az1324, you are my hero! I love simple solutions, especially when they save me time and money.
Thanks everyone,
david

 

[az1324]

Yep you got it. Glad to help.

 

[robertmee]

If YOU really want to use relays you could get creative and use a binary setup, but it would take lots of contacts on each relay (unless you broke them up into sets and then it would take 2 or 3x as many relays).

You could do this with a relay matrix and only 6 SPST relays. 3^2=9

So using one 8 relay board you still have 2 extra relays.

D'oh....I should of thought of that, having worked on many a Pinball Matrices.