question

pv-bauer avatar image
pv-bauer asked

cerbo, set digital input to tank (blackwater)?

Hello,
is it possible to configure a digital input as a tank?
To see - in the tank overview - that the blackwater tank is full.


In a camper I have a Thetford cassete toilet.
Insinde the black water cassete is a swimmer with an magnet.
Outside the black water cassete at the housing is a reed contact which switches ON a red LED for warning, that 15l of 17l (~88%) black water capacity is reached.

The LED is broken and i still replacing it by an new LED and parallel an optocopler to trigger one digital Input ports of the cerbo.
(At this model, the reed switch is in the (-) wire of LED. In the (+) wire is a resistor.
I replace the resistor by a small current source pcb for LEDs.)

But I can't find a setting to set the digital Input to "Tank" or "Blackwater Tank" to see it in the tank overview.

cerbo gx
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2 Answers
Alexandra avatar image
Alexandra answered ·

The digital inputs are open collector inputs. So open or closed. Not suitable for your application. There is a dedicated input for tanks.

Maybe you can customise (you can rename inputs) and somehow use two for each level. But not sure how that will integrate into our choose of level indicator.


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pv-bauer avatar image pv-bauer commented ·

Hi Alexandra,
I knew that the tank inputs are for resistive inputs. (Freshwater and Greywater)
But I don't want to drill holes in the blackwater cassette to add a resistive measurement system with electrical connetor. Just want to use the reed contact full indicator.
I still hoped it would be possible to display the digital input on the tank overview.
No detailed levels, just no alarm = blackwater ok (empty) / or alarm = blackwater full.

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pwfarnell avatar image
pwfarnell answered ·

The categories are limited, I would suggest setting it as a bilge alarm and then naming it as "toilet level alarm" which is what it will appear as in the device list. You can set an audible alarm from this if you require.

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pv-bauer avatar image pv-bauer commented ·

Hi pwfarnell,
I still test a lot of settings yesterday. Well I found a similar way, set as bilge alarm,
change to "Oh shit blackwater 88% full!" Audible alarm works too when the contact is closed.
But I'am still unable to display this "blackwater ok " or "blackwater full" in the tank overview.

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pwfarnell avatar image pwfarnell pv-bauer commented ·
You will not get it into the tank overview from the digital input, you will only see it on the device overview.

If you want the level switch as a tank then I have an idea that may work. Take the reed switch and connect say a 100 ohm resistor in parallel and connect these to one of the tank inputs. When the level is low and the switch is open the resistance will be 100 ohm, when full the switch closes and the resistance will fall to 0 ohm. Set the tank up with a custom resistance range of 100 ohm to 0 ohm from empty to full. Bingo, you will have a binary tank level gauge.

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derrick thomas avatar image derrick thomas pv-bauer commented ·
It will not display in the tanks overview. It will display in the device list or the combined overview page (can't remember what it's called in the display menu settings). Maybe boat and motorhome overview?
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