Category Archives: Build Progress

Multi-Target KNX Home Automation Configurations

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Generally speaking I get on very well with the KNX Home Automation standard and the ETS software used to configure a KNX installation, but every now and again it catches me out.

A recent situation was for the automated garage doors. Those are Hormann RollMatic 2 roller shutters and each one has a Hormann KNX Gateway attached to its HCP Bus. While these don’t provide a huge range of functionality, they do make it possible to open and close the roller shutters from the KNX Bus (e.g. using Home Assistant) and to trigger other actions when the shutters open and close.

The behaviour I wanted is that whenever one of the doors starts opening, it:

  • Switches on the two Indoor garage lights either side of that specific door
    • There are no windows in the garage and the garage doors are North-facing so it’s generally always desirable for the indoor lights to come on – though I’ll review that again in the Summer
  • Switches on the two Outdoor garage lights either side of that door
    • But only if it’s dark outside
  • Switches on a relay to tell the alarm system that a door is being opened

The Hormann KNX Gateway provides both a “Door open status” and a “Door closed status” output. At first glance “Door open status” looks like it will provide the necessary trigger but in fact that only changes state when the door is fully open – i.e. at the end of the motor travel. Fortunately there are configuration options to flip the “Object polarity” for both these outputs, and by selecting “Door closed status” to be “0 = Closed” (as shown below) that effectively becomes a ‘Not-Closed’ output, which changes to 1 as soon as the door starts opening.

Part of the KNX ETS Configuration screen for the Hormann KNX Gateway, showing the two “Object polarity” options

The Hormann KNX Gateways were a relatively late addition to the installation, due to availability issues, so I’d previously configured separate KNX Group Addresses for each of the Lights to enable manual control using the Home Assistant app.

The mistake I made was to link the Hormann KNX Gateway’s “Door Not Closed” output to the multiple Group Addresses I’d already configured – and the problem is that only one Group Address can be configured as the “Sending” destination for an output object. Initial testing showed that my multiple-GA configuration sort-of worked – e.g. the indoor lights initially came on when a door opened – but once the other targets were configured the indoor lights stopped working.

The fix was to link all of the lighting relay channel switches directly to the same Group Address as the “Door Not Closed” output, so the latter is only “Sending” to that one GA. There are still dedicated Group Addresses for the lights, for use with Home Assistant, but those are no longer targets for the “Door Not Closed” output.

To complete the picture, the “But only if it’s dark outside” logic is addressed using a Group Address which tracks whether it is “Daylight” or not, and configuring that as a “Lock” for the relay channels connected to the Outdoor lights. When the Daylight GA is ‘On’ the Lock is active and the status change from the “Door Not Closed” output gets ignored for the Outdoor lights. The setting and resetting of the Daylight GA is performed using the existing Home Assistant Automation rules which run at Sunrise and Sunset (although using a KNX ‘Twilight’ sensor would be an alternative and more natively-KNX way of achieving that).

The only remaining minor issue is that some of the Indoor lights switch off when one of the garage doors gets to be fully closed – which is annoying when planning to continue working inside the garage with all the doors closed. That means using the light switch (or Home Assistant) to turn them all on again. In principle, it would be possible to use the motion sensors which are part of the alarm system to control (some of) the lights, but that integration isn’t currently in place.

Outbuildings: 2026-01-22 Update

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Outbuildings: 2026-01-22

While almost all of the building work was completed before the end of 2025, there were a few items outstanding which have been attended to over the past couple of days:

  • The rainwater drainage inspection chamber in the North-East corner of the Courtyard (top-left of the overview photo) has always been holding 30-40mm of water – implying an inadequate ‘fall’ on the outlet pipework.
    • The fall was checked with a laser level on Tuesday, which confirmed the chamber was set at the right level and pointed to some sort of issue on the downstream pipe run.
    • Excavation of that pipe run showed there was a ‘hump’ in the pipe which was causing the issue – partially due to it passing over a separate underground pipe connected to an Aco doorway drain.
    • With the pipe run re-routed away from the other pipe and re-levelled at the correct fall, the rain is now draining out of the inspection chamber.
  • The ground in the Courtyard has always been prone to holding pools of standing water – which was evident before construction started. As a consequence, a network of ‘land drain’ pipework was installed, formed from four ‘legs’ running east-West (which will end up in the middle of future planting beds).
    • The expectation was that there would at least be no standing water in the immediate vicinity of those land drains – but that wasn’t the case, and in fact there were some pools of water directly above the drains.
    • The issue turned out to be the use of solid clay as the back-fill material over the land drain pipes – and in some cases inadequate pea gravel over those pipes.
    • The agreement with the build team was that they would remove the layer of clay overlaying the land drains and top-up the pea gravel cover over the pipes to the specified 100mm depth – and then I will fill the trenches with some more free-draining soil from elsewhere on the site, as part of the work required to prepare the soil between the drains for planting.
  • Some other finishing touches that happened to be scheduled for today were for the windows and doors.
    • One of the window handles was from a faulty batch, and the lock cylinder kept falling out – so that handle was replaced (from a new, good batch).
    • There was some install-time damage to one of the door handles, which was also replaced.
    • The original window sills turned out to be too ‘deep’ to fit properly so those were re-made and fitted today.
    • A minor manufacturing defect on the bi-fold door meant the bottom seal had been torn – and would be torn again if one of the hinge fixings wasn’t adjusted, so that hinge was re-fitted and the seal replaced.