Systemair SAVECare Ventilation unit

[prilly (babblarna)]

That is wired very wrong on your dongle side, you have gnd, and tx/rx mixed up

Double check your wire diagram

From left on your dongle

Pwr ground, black
Then brown +24v

Modbus
Blue
Then yellow/green

[MotiejusK]

Many thanks!

[prilly (babblarna)]

Works now?

[MotiejusK]

Reading works. Writing not yet.

[prilly (babblarna)]

Hi Darius

I am trying to get demand controll working with co2 input, not only internal rh,

Is it possible to assigne a AI to co2 and then write to this register from modbus to set the value?

[Anacron]

Hi, do you have Systemair CO2 detector connected to unit input or you have some third party CO2 detector? I’m using third party SCD30 detetor and HA sends data to unit via Modbus and this setup works fine. If this is your use case, I can help you to get it working.

[prilly (babblarna)]

Hi

Yes i have multiple co2 sensors, airgradient ones connected to ha. Running some calculations there getting the highest value of them all. My idea was to use this value, but i was uncertain how to write them to unit.

I had two approches, either use a 1-10v analog output directly coupled to the AI input of the unit or write the value with modbus to the AI input register while nothing is connected to the input itself.

My question was if its possible to modbus write to the AI input of the unit to set its value.

Could you elaborate how this works in practice? When a value is written, this value is set until next write? Does the unit at anypoint reset this value?

[Anacron]

You have similar use case as me You can use register 12113 as Darius wrote some times before. I have automation which send once per minute CO2 value to register. Probably you know that, but in HA you have to decrease register number by one, so correct register in your automation will be 12112.

Systemair SAVECare Ventilation unit

@PatrickJanson Yes, there is such a register, actualy for both CO2 and RH sensors. REG_SENSOR_MODBUS_CO2 12113 Holding public 0 2000 ppm ModbusCo2Sensor REG_SENSOR_MODBUS_RHS 12114 Holding public 0 100 % ModbusRhSensor PPM value is expected here for CO2 sensor (range 0 - 2000 ppm) Which registers do you use to override fan controls right now? Be careful though, all settings goes into NVM, which has a lifetime of around 300,000 writes, so if you use it too often - you will kill …

Please note, that max value is 2000 ppm and I didn’t test what will happen if you exceed this value. The unit can set maximum allowed value, but it also could ignore the value, which could cause problems.

EDIT: Don’t forget to activate CO2 detector in IAQ options of your unit and set mode to AUTO.

[prilly (babblarna)]

Thank you, just what i need

[tesharp]

For anyone with Save Connect 2 unit I have started on a new custom integration: GitHub - tesharp/systemair: Home assistant integration for Systemair SAVE Connect 2 using modbus over web.
Only tested on my own unit so might be sensors missing

[prilly (babblarna)]

Over web? So you are relaying on the systemair cloud?
Do they expose control of the unit with modbus?

[tesharp]

I’ll change the description to “over http” instead of “over web” to make it more clear. It connects to the unit on local address using mread / mwrite as others have used

[dtswk]

Thank you…! I have the SaveConnect 2.0 but have used the EW11. I found that the SaveConnect would hang as well as the display in the VSR3000 from time to time. Have you had any issues? FYI - the EW11 alone has been rock solid.

[moskovskiy82]

Not a programmer myself but looks like it could be easily used for local usb modbus connection?

[prilly (babblarna)]

There is a problem with save connect (that has tcp modbus) and save connect 2 (that has no modbus)

Save connect do not respond to heavy modbus traffic very vell it do lack cpu power for this, modbus vas removed from connect 2 for this reason.

Its better to either use the systemair official modbus rtu to tcp convert Modbus Gateway Control · Systemair or use your custom one.

I did have severe modbus issues with the connect unit, after switching to the modbus gw from systemair i have a much better result, even though i also need to run the baud rate at 9600 to achive stable rtu communication.

If you plan to integrate your ventilation unit you should get yourself a modbus rtu/tcp gw for best result

[Anacron]

I don’t have so much experience with SAVE unit yet (I use it only for three months), but I don’t have any issues with EW11A convertor. Even if I update some entities every second. The Systemair Modbus Gateway is very expensive (like 1000 €) so I decided to use EW11A instead and I’m very satisfied. I’m just missing some integration. I already integrated some basic entities, but doing it one by one thru yaml is for long time. I’m programmer, but I work in Java so for meit’s long-term task to create integration

[prilly (babblarna)]

There are many alternatives to the systemair gw that indeed is expensive, ew11a is perfectly fine and will be a better alternative then using the save connect as gw