IOShield question

[Felix]

I think this is very similar to my controller, except mine is not shrouded in this white plastic and I could see everything as shown in my IOShield demo video. It's also the same brand.
If that assumption is true...

In the upper left of the picture is a set of vertical pins.  They are connected to the controller via a ribbon cable.  This is where the IOShield taps into for power and to control the solenoids.  The top pin is 24VAC as measured with my voltmeter between it and the light green wire which is ground.  The second pin is ground for the controller.  When I hook up just these two pins, the controller powers up.  It is these two pins that I have used to power the IOShield.  The bottom 10 pins are used to control the different zones.

... then this is what I did:
- once I identified the 2 power pins (24vac and GND), I swapped them so the controller GND is my 24VAC. This whole thing is floating if it's going through a transformer so GND can be anything you want safely without any ground loops issues (if this was galvanically connected to real earth GND). So that gave my my IOShield a positive voltage that was negatively biased with relation to the rest of those pins (the zone pins) in the vertical connector. So the outputs from my IOShield would basically connect straight through to those zones and activate them. You can try the same thing step by step.
- invert the power inputs, IOShield should power up
- you now have 3.3V power coming from the Moteino - measure between this 3.3V and any of your zone pins. There should be a negative bias (as if the 3.3v were the ground of the measurement). If so try to manually connect the IOShield 3.3V to one of these zones, and if my theory is right then that zone should go ON. At least that's what worked for me. These solid state TRIACS need very little bias to turn on. If that works, then the IOShield will do the same, apply 3.3v to the outputs and then you can just connect the IOShield outputs to the zone pins and you're done.

To avoid damage to anything, if you're not clear keep asking questions and I'll try to be more detailed but now that you're fairly familiar with the innards of your controller this should make sense.

I know this is confusing to newcomers but it's just the way these controllers work and that's what you need to get them activated without really spending a lot more money on designing a whole new unit. I opted for a simple shield that when wired correctly will just make for a nice extension and minimal spending and waste. The key is in finding that virtual ground that you use as the high side of the VAC source.

[ssmall]

Felix,

I wired up the IOShield  as you specified by using the two pins that power the controller.  I swapped 24VAC and GND to power the IOShield and connected output pin one from the IOShield to zone one on my sprinkler system.  I then activated the IOShield pin from the web interface.  Unfortunately this did not activate the solenoid .  If there is something else I can try or if you would like me to post a picture of what I did, please let me know.

Thanks

[Felix]

Without tapping into your controller I cannot determine what is required to be wired. Me just saying do this or that doesn't mean it's going to work, it's only an indicative based on some assumptions. You will need to verify those assumptions and actually be able to find what will trigger the TRIACs. That's all there is to it, find what will trigger the TRIACs. If you indeed have TRIACs, they should require little voltage on their bases. I used a small Lipo battery to do the testing once I theorized what needs to be done (rather than just wildly connecting wires just to see what happens ... or what blows up). When you can trigger a TRIAC with a Lipo (which is close to the 3.3V operating voltage of the IOShield) then the battery GND becomes the IOShield GND, the rest I think I already mentioned before.
So find what will trigger the TRIACs. The front panel (the one that connects via the ribbon cable) does just that. Find the digital GND of that, and then figure out what the other zone pins do when they activate the TRIACs. Then repeat that with the IOShield and you are done.

[ssmall]

Just wanted to wrap this up.  I wasn't able to get the IOShield to control my sprinkler controller.  I decided to get a bank of relays and use the IOShield to control relays.  I hooked up the relays directly up to the valves.  The relays were 5v, so I just needed to switch the IOShield over supply 5v and I was done.  The IOShield is great piece of work!

[Felix]

Thanks for the follow up, indeed the relay approach is probably easier than trying to do direct logic driving of the TRIACS. Good work Steve