I try not to be a burden by asking too many questions but I am a little surprised by the unusual lack of information in the Multiplus II Manual.
When I try to clarify the functions of AUX 1 & AUX2 all I get is what I see in the attached image with no reference to whether the contacts are NO or NC when nothing is connected to them.
Have I missed a page in which case would someone be kind anought to point me to it?
Are they designed to accept typical (CMOS/TTL) logic voltages (<2.5=low >2.5= high) or up to 12V too?
I’m attempting to use the input with assistants controlled by the Cerbo GX.
They are not Relais, so there is no NO/NC as the input does never have a state.
However, they are 5V inputs, with an internal pull up resistor, so if you have nothing connected it will be logically high, if you shorten it, it will be read logically low. Tresholds for Low/high are 1V / 4.0 V iirc.
This is excellent, many thanks indeed I wonder why I didn’t find this documentation in my searches.
So, in short, is it safe to connect the Cerbo GX relay 1 to the Multi Aux 1 in order to short the pins thus creating a “Low” signal which in turn will be read by the Assistant to perform a function?
Yes. I use exactly this to drive the AC Out2 relay on my MP2
Word of caution: if you’re connected to the grid, make sure AUX1 isn’t reserved by the grid code settings !
It is the case for Belgium, Germany and many other grid codes, where the Aux1 signal is used as a “Disable FeedIn” signal.
yes, this is very common. this way you are able to use the generator start stop functionality to trigger actions on the multiplus side. the aux is really just a digital input.
Could you expand on that? I don’t think it’s my case since I’m the only person who has worked on this project but I would like to know more about this function and how or why it would be implemented.
Thanks
Interesting I expect that “feed-in” is intended as in “feed into the grid”.
So, would they set it to the state “unable to feed” as standard (when in a “pulled-up state”) or would they send a signal short-circuiting the pins to do that? Just curious
I want to use it to activate AC in while, at the same time, with a second Assistant, opening the AC-Out 2 circuit (to the off state) for a specific reason that I won’t bore you with unless of course, you want to know
Thanks for confirming,
so am I correct in saying that the polarity really does not matter since it’s only closing the circuit (short-circuiting the Aux1 pins)?
Always a good thing to double-verify that the device you’re using to open/close the input is a potential free “dry contact” such as a relay.
Other switching devices can be of the pull up (to 5V or 24V for example) or pull down (to 0V) type.
Those can be used as well but then voltage and polarity are important.
In a system with shared ground, you don’t want to put +24V onto the grounded pin of the input
If you’re using the relays of a GX: those are potential free relays so no real need to check for polarity.
For the standard operation of the “Disable Feed In” signal: if I remember correctly, you need to close (short) the input to activate the function, that is: to disable feed in.
To legally connect your system to the public grid you need to be grid code compliant, so I strongly advice to configure the correct grid code.
From your profile I see that you’re in the UK and the grid codes for UK also use AUX1 for the “Disable Feed In” option.
I say grid codes because the UK has two (Brits… ) : G99/1 Amendment 8 and G98/1 Amendment 6 which tends to be 16A max.
Up to you to figure out which grid code is applicable to you I’m afraid.
That is exactly why I was enquiring, not knowing the internals a wrong scenario could easily develop.
For the rest, I have built this system to work off-grid with the only inbound grid line devoted to potentially charging the batteries during lower tariff hours.
To do so avoiding mixing up the two lines, I want to use the assistants as follows:
Assistant 1 uses a general flag to ignore AC until such time when it receives the go-ahead from Cerbo (start generator) Works Great and charging commences.
Assistant 2 was set up to disconnect AC2 Out when ACin is present because I assumed that it would read that after the “ignore AC In” point, in fact, as I discovered minutes ago, that is not the case so it only disconnects AC2 out if I physically turn the Grid input breaker off.
That means that the idea in principle was correct but the signal unfortunately is picked up at the physical AC in connections rather than after the “Ignore” stage
So I’m back to the drawing table to see if I can find another way to disconnect AC2 Out when the charger comes on which is in fact when the “Ignore AC in” is disabled.
As I’m not familiar with the list of assistants yet, so any suggestion is more than welcome of course
By default, AC Out2 is active only when AC In is active, but that behavior can be overridden - that’s what I’m doing.
Can you describe what it is you actually want to achieve ?
What input condition should activate or desactivate which behavior ?
With VRM you can pull the active config from your Multi and then you should see the grid codes.
As I learned from another post of you, this might be a system with 2 parallel Multi’s.
In that scenario the AC INs are connected to each other and also the AC OUTs.
If you want to manipulate them with assistants, those assistants should be configured in both Multis.
And if you’re using AUX input signal to do so, you should connect those to each other as well.
There is some synchronization over the VE Bus cable, but not the status of input signals or relay drivers
My object is to use the Cerbo Generator On to activate AC In so to start the charging and that works fine with the assistant I’ve created.
At the same time, I want to disconnect AC2 Out because that is going to be my primary and only line out to my Building 2 (I’m using the grid from Building 1 to charge only and at that time also building 2 receives energy from Building 1 directly by a switch over system)
So I have now created another pair of assistants to switch AC2 out to off also controlled by AUX 1 hoping that will work since the previous one did not.
Assistant config below should do what you want, I guess.
I’m using AUX2 as I’m running ESS and have the Belgian grid code active, which uses AUX1 as “Disable Feedin”.
When AUX2 contact is shorted, AC OUT2 is active and AC IN is ignored.
When AUX2 contact is open, AC OUT2 is inactive and AC IN is active (to charge).
These assistants should be active in all members of a parallel system and the AUX2 pins of those systems should be connected as well.
Depending if you’re using an active high (input open) or active low (input shorted) signal you might need to invert the On and Off actions.
Thanks, I can see the meaning of flag ignore AC input 1 but I’ll have to understand why two more flags for the other relay on & off, I thought the flag could only be used with the “ignore Ac” command.
Do you add a general flag to every relay?
I’ll have to look into it more tomorrow.
I might come back to you on this if you don’t mind
here is what works for me in order to ignore ACinput 1
My first two relay assistants drive the actual AC Out2 relay, on and off, based on the state of AUX input.
My last 2 relay assistants drive the virtual “General flag” relay, also based on the state of AUX input.
The virtual “General flag” relay drives the “Ignore AC In” function.
Don’t read the assistant setup as a if… then… next… sequence.
All assistants are active in parallel.
I wonder why I didn’t find this documentation in my searches.
I expect that “feed-in” is intended as in “feed into the grid”.
) : G99/1 Amendment 8 and G98/1 Amendment 6 which tends to be 16A max.
