OpenSprinkler LATCH wiring?

[Blardo]

I’ve looked through the forums/FAQs for a while and haven’t seen a clear answer. When using the OS LATCH controller with a bi-polar solenoid (https://www.hunterirrigation.com/irrigation-product/solenoids/458200) do the wires take up 2 valve positions?

[Ray]

The OpenSprinkler user manual explains:
https://openthings.freshdesk.com/support/solutions/articles/5000716364-opensprinkler-user-manuals
just search ‘latch’ in the document.

[Blardo]

Thank you for the reply, I found the following:
Installation->Instruction-> Step2->Bullet 2 says “For DC-powered OpenSprinkler and OpenSprinkler LATCH: The COM terminal is positive (+). If your solenoid wires have polarity, ensure the positive wire (typically red) connects to COM. Insert the DC adapter into the power barrel.
5. Advanced Settings -> “Latch On / Off Voltage: Applies only to OpenSprinkler Latch. It customizes the voltages generated by the booster to activate and deactivate latching solenoid valves. The maximum value for each is 24V.”

Does this mean that the Valve will use the common as the reference when latching? Assuming 12VDC power, 3VDC latch on voltage, 21VDC latch off voltage, it will pulse with a +9VDC potential on and a -9VDC potential off? Like the attached drawing?

Attachments:

1. 

   Latch.png
   

[afont]

Hi… have just installed a latch and having issues with turning valves on and off. Found no configuration instructions. Is this configuration correct?

[Ray]

OpenSprinkler user manual is here:
https://opensprinkler.github.io/OpenSprinkler-Firmware/2.2.1/221_4_manual/
If you want to see Latch-specific settings, just search “latch” in the manual.

[marten]

@afont – I’m also having trouble with my latching valves. I can’t get OpenSprinkler to get them to do anything. I’ve found the 3 latch-related settings in “Advanced” but nothing I’ve tried so far has helped. Did you figure out your problem?

[Threaded]

@marten I have not got as far as testing my latched valves with the “OpenSprinkler 3.3 LATCH” model, I am waiting on some parts. I’ll report how it goes.

[Blardo]

@afont, @marten,

I was mistaken as to how the circuitry works. Referencing this blog post: https://opensprinkler.com/introducing-opensprinkler-bee-2-0-a-wifi-enabled-universal-sprinkler-controller/ you should set the latch on and off voltage to the appropriate potential needed to latch (usually the voltage on the side of the solenoid)

Ray does make a comment in post: https://opensprinkler.com/forums/topic/i-have-a-few-questions/#post-83566 That if the boost voltage is set below the input voltage “It will do nothing and will not drop …” I am not sure if this means that the boost circuit will do nothing and pass input voltage through OR that nothing at all will happen and the input voltage will not pass through.

I’ve simply made sure to set my boost voltage above my input to not have to worry about it.

There are some solenoids that I’ve found do not work with the OpenSprinkler LATCH, namely Bermad S-402-3Ws (https://www.galasa.es/documento_oferta/219). These have a manufacturer recommendation of 4700uF to latch them and the OS LATCH only has 2200uF. At some point I plan to swap out the cap and confirm that with the larger capacitor it works, but haven’t had the chance.

[Blardo]

afont,

I was confused by the manual as well. This blog post is much clearer about what is going on: https://opensprinkler.com/introducing-opensprinkler-bee-2-0-a-wifi-enabled-universal-sprinkler-controller/

One thing that I haven’t had a chance to check on is if your boost voltage is set below your input voltage. In this post (https://opensprinkler.com/forums/topic/i-have-a-few-questions/#post-83566) Ray mentions “So if your input is 12V, you can only set the boosted voltage above 12V (up to 24V), if you set it to 9V, it will do nothing and will not drop to 9V.” I am unclear whether “it will do nothing” means that the boost circuit will not boost and it will pass the input voltage or if the entire circuit will do nothing and no voltage will go to the zone. I’ve just made sure to set my boost voltage above my input voltage and it has worked for the most part.

[Ray]

@Blardo: Please understand that you are referring to different products: this post is mainly about OpenSprinkler Latch – it’s one of the OpenSprinkler mainline products that runs the unified OpenSprinkler firmware. Your recent two posts about OpenSprinkler Bee – it’s a small controller that only handles 3 zones and runs its own firmware. Nonetheless, the wiring convention is the same on both: COM is positive (red wire) and individual zone ports are negative (black wire). So the wiring is consistent between the two products.

Also, the reason the boost voltage cannot be lower than the input voltage is that this is an inherent property of a boost regulator circuit – it can only ‘step up’ voltage, it cannot ‘step down’ voltage. More technically, there is a directly path from the input voltage to the capacitor that stores the boosted voltage (via a diode that prevents back-flow). Because of this, the capacitor voltage will be at least as high as the input voltage, it cannot be lower than that.

[Author]

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