[APP][Pro] Duco modbus

Hi All,

I’ve an app submitted in the App-store for testing. This is an app for Duco ventilation products based on Modbus (TCP). [[Repo]

Initial beta release is meant for stability tests and for now it only supports the master box (focus, slient), but other products like valves and room modules will be added later on (incl auto discovery of the masters sub-devices).

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How does homey connect with the ducobox ?
With protocol is used.

Can only read the params or even controll the fan speed

Good work !

it’s through modbus TCP and it should be compatible with any Duco ventilation system. Duco is very consistent in their modbus registers.

The app now only reads parameters but using the Holding registers you can control / override the devices.

I think the best way is using the lower level limit, this way the Duco ventilation system can always “overrule” your setting in case of high humidity, temperature or CO2 levels.

Connectivity Board is a additional board i will assume ?
Quick googlr search learned this is 200 euro board something right ?

For the older duco ventilation boxes (focus, silent before 2017) there’s modbus rtu integrated. If I’m correct from 2017 there’s an additional TCP interface board required.

I thought the price was around €180.

Best regards,

This is great. :slight_smile: Let me know once the test version is available in the app store.

So, update from my side.
Node (modbus) discovery is now integrated. Now implementing node (device) specific features.

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Nice! Can you post it already on the apps tore? Or wait a bit until everything is working stable?

There is one version pending for acceptance, after acceptance I can release test versions.
There has to be done a lot before everything works. I’m still learning every day :laughing:

New to homey DSK and javascript/NodeJS (I’m a realtime embedded systems developer).

But I’m very impressed how Homey build their platform. It works very nice (documentation could be better).

The app runs stable, I run longterm tests daily. It doesn’t crash and if communication fails, it recovers by itself. And using limitted resources, could add up to 100 nodes.

Step by step, we’ll get there.

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@Nickk @MarcoV
I’ve got a beta available in the store :

All read properties for now and Flow level is not the real flow level, Duco said it’s the valve position (not an actual flow measurement).

Best regads,


@Tjar Could you help me out a bit? I have a Focus with the communication print and fixed IP adress, but I am not able to add the device using the prefilled settings. Is there a modbus on/off setting hidden somewhere?

Hi Gijs,

What kind of communication print do you use? it looks like it’s Modbus RTU setting.

You have partnr? Or URL?

Best regards,

That will be this one: DucoBox Communication print | Ventilatieland

Hi Gijs, what kind of duco box do you have? silent, silent connect, focus, …?

I have a DucoBox Focus.

hi Gijs,

I’m not familiar with the communication board. If I’m correct the default settings are 9600baud, no parity and 1 stopbit, ID:1 and address offset 1.
I think the “address” field is the ID field.

I’ve a Moxa Mgate on my Duco focus. That works (set to higher baudrate).

Best regards,

Ah, looks like the communication board doesn’t allow modbus TCP/IP. Well, I’ll get me a converter then. Thanks for your help! :slight_smile:

the manual says it supports modbus tcp:
“02.F Can Modbus TCP be read by default on a DucoBox?
Yes, a Modbus converter is no longer needed as with Modbus RTU.”

I don’t really understand why you should configure the RTU, except when the communication board interfaces with the ventilation box using modbus RTU.

Best regards,


you may try CAS modbus scanner. Just try to connect to the IP and port 502, ID:1 and read the (single) address 10 (holding or input, doesn’t matter).

Best regards,

Yeah, to make things easy :sweat_smile: That is the ‘connectivity board’ (seems to be the newer version of the communication print, which I have). Checked with CAS modbus scanner to be sure, but no luck. Luckily there is sill the solution of the converter.