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Endre Kiss avatar image
Endre Kiss asked

VE.direct with external device

Dear All,

It might be a newbie question but I did not find any proper answer to my question. I'm building an Arduino based little automation for reliably turning on and off a water heater when excess solar is present. To do this I would need the SoC and the MPPT 100/50 solar input voltage. All my stuff (MPPT charger, Multiplus and BMV712) is connected to a Cerbo GX. As I have one VE.direct port left can I use this to enquire the SoC and MPPT input voltage from Cerbo GX or these must be directly from the BMV and MPPT requested?

Thanks for reading, Endre

VE.Direct
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3 Answers
wkirby avatar image
wkirby answered ·

No, the CerboGX's VE.Direct port is only for consuming data, it does not provide data at all.
It would be tricky to get the data you want over VE.Direct if you are already using the ports to connect to the CerboGX.
The data you want is accessible over ModbusTCP, but you'd need the Ethernet Shield to query the registers on the CerboGX over ethernet.

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Endre Kiss avatar image Endre Kiss commented ·
Ohh I see... So, that is not an option. Thanks a lot for explaining! I was suspecting that might not be available all data on any of the VE.Direct ports only to the attached equipment's.

Thanks!

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hjohnson avatar image
hjohnson answered ·

This might be a stupid question, but why bother with the Arduino in the first place? You have a Cerbo GX. I would just switch to the large image and achieve what you want to do using NodeRed running on the GX itself.


Between the access to the data from the Victron environment, and the internal relays on the cerbo you have everything you need. Additionally, you can be more intelligent about things and base the dump liad decision on SoC and the like.

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Endre Kiss avatar image Endre Kiss commented ·
I didn't even know about the existence of a "large image". That sound interesting but to be honest is a completely new field this NodeRed, I hope is not a mined field :-) as I'm not a programmer only a hobbyist.

In fact I went trough several options how to do this, using the BMV internal relay it self is not enough as you are not sure that your demand is on sunshine or after sunset (still above 95% SoC), but none of them convinced me. The idea is to have secondary data, Vmppt, which tells the fact that there is a sunshine, also can be added the MPPT charger's power headroom as a third parameter. Thanks for the hint I'll have to dive in NodeRed...

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johanndo avatar image
johanndo answered ·

You cannot use the Ve.Direct on the Cerbo for this, but you can use WLAN / LAN connections to communicate with the Cerbo easily. You can use the Cerbo itself to manage your energy dump device or even easier use the BMV and his built-in programmable relay directly to control your heater based on SOC and battery voltage.

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Related Resources

VE.Direct protocol FAQ