The Keypad Can Tell You Someone Is at the Gate

I have been reading through the ETS manual for Faradite's TAP-5 KNX coupler this week, and there is a feature buried in there that I think is badly underused across the industry, mine included.

Not the status LEDs. Every serious KNX keypad has had those for as long as I have been doing this. A light on the button showing the circuit state or the active scene is standard, it is expected, and there is nothing to write about.

The thing worth talking about sits alongside that and has nothing to do with the buttons at all.

Two different things that both happen to be LEDs

The TAP-5 has RGBW LEDs embedded around the outer edge of the coupler, and the manual splits their use into three functions with a strict priority order. Orientation lighting at the bottom. Status feedback in the middle. Notifications on top, overriding both.

Status feedback is tied to the button's function. Press the corner running the kitchen scene, that corner lights. It reports on what you control from that plate. Ordinary.

Notification objects are independent. You get up to three, they are enabled separately in the General menu which then reveals a Notifications tab in ETS, and they appear as group objects 35, 36 and 37. Each one is a 1 bit input, DPST-1-1. None of them are attached to any button.

The manual is refreshingly blunt about the implication: these can theoretically be linked to anything in the KNX building via a 1 bit object.

That is a different category of behaviour. The first is a switch reporting on itself. The second is a wall plate acting as an alert surface for the entire system.

What you actually get to configure

Worth laying out properly, because the options are what determine whether this works or annoys everyone.

Effect. Halo rotate, where the LEDs appear to travel around the plate. Flash, where all four corners pulse together. Or permanently on for the duration.

Flash speed, if you chose flash. Very fast through very slow, medium by default.

Colour. Warm white, red (the default), magenta, blue, cyan, green, yellow, plus three custom colours you define globally and can reuse across status, orientation and notification LEDs.

Brightness. Ten levels, with the manual describing level 1 as subtle in a dark room and level 2 as visible in a dark room. Day and night mode can carry different brightness for each, so an alert can be dim at 2am and obvious at midday.

Duration, and this is the important one. Either permanent, meaning the LED follows the object, on at 1 and off at 0. Or timeout, meaning it fires and holds for a set period then reverts to whatever the priority stack says should be showing. Timeout is settable from 0 to 255 seconds, default 10.

Priority among the three runs 1 over 2 over 3, so your most important alert belongs on Notification 1. Easy to get backwards.

Permanent or timeout is the entire design decision

Everything good or bad about this feature comes down to that one parameter, and it is where presence sensors get interesting.

A presence sensor produces a state. A notification object consumes a 1 bit state. Connect them and the house can tell you where people are without a camera, a phone or a subscription. Someone in the driveway. Movement in the store room. Occupancy in the granny flat. A child's door at two in the morning.

Except bind a raw presence output in permanent mode and you get a keypad that glows for as long as anyone is in the driveway, which on a Saturday afternoon is most of it. Four days later nobody sees it. That is how this feature ends up switched off.

So the rule I would work to is simple. Events get timeout. Conditions get permanent.

An arrival is an event. Someone has just come into the driveway, flash it amber for twenty seconds and let it clear itself. A gate standing open is a condition, and it should sit there in permanent mode until the gate actually closes and something writes a 0.

Which leads to the constraint nobody mentions. Timeout maxes out at 255 seconds, four minutes fifteen. If you want a timed alert to persist longer than that, timeout mode will not do it. You use permanent mode and write the 0 yourself from a logic block or from Home Assistant when the condition clears. That is a small thing that will bite you at commissioning if you have not planned for it.

The other half of the presence work is that you rarely bind the sensor directly. You bind a derived condition, and the logic lives in ETS or Home Assistant depending on complexity. Presence in the driveway and the alarm is armed. Movement at the back gate and it is after 22:00. Occupancy in the granny flat and nothing has been detected there for six hours, which tells you somebody arrived rather than that somebody is present.

That conditional layer is the actual engineering. The LED is the easy part.

The doorbell case, and why it is better than it sounds

The manual's own example is a notification linked to the doorbell, flashing green for a minute. Their second is red when the front gate is open.

The doorbell one sounds trivial until you think about the failure it fixes. You are at the back of the house, there is music on, and the intercom handset is in the entrance hall where it has always been. Nobody has reliably heard a doorbell from the far end of a house since houses got bigger than the bell was designed for.

Now every plate in the building flashes. No app, no phone, no account, no notification permissions. A guest sees it. Someone working in the house sees it. One group address, one object.

And because you configure this per keypad, you can target it. Faradite's other published example puts a garage-left-open alert on the downstairs keypads only. The alert goes where somebody can act on it rather than everywhere.

What else earns one of the three

Three objects per keypad is a hard budget. Split by whether they are native or need a bridge, because that gets glossed over.

Gate or garage left open. Native, off a contact, permanent mode. Probably the highest value one in a Johannesburg house, because it is the most expensive mistake and completely invisible from inside.

Leak detected. Native, permanent. Should be audible too, but a light on every plate is a good backstop.

Tank or borehole level low. Native off a level sensor, permanent. Given how the municipal supply behaves, knowing before the taps run dry is worth an object.

Alarm armed or not. Native if the panel has a KNX interface or a spare output, permanent, on the plate by the door you leave from.

Running on battery rather than grid. Not native. Off the inverter over Modbus into Home Assistant and back onto the bus as a 1 bit object. Worth doing, but it is a longer chain than a contact on a gate and should be specified as such.

Nothing purely informational. No temperature readouts, no washing machine finished. Every object has to survive one question: is this rare, and can somebody do something about it.

The discipline is harder than the engineering

A light that is on half the time is wallpaper. This is the failure mode that kills these installations, and it is almost always a permanent-mode binding that should have been an event.

Notifications override status feedback. The priority order is correct, but a notification stuck on takes over the plate and your scene feedback disappears. Overspend the budget and you break the keypad's day job.

One colour vocabulary across the whole house. Red means the same thing on every plate or it means nothing. Decide it once, write it down, hand it over with the documentation. Three custom colours on top of seven named ones is more than enough rope.

Put the alert where it can be acted on. A gate-open light in the guest bedroom is decoration.

Check which way the failure points. If lit means movement detected and dark means all quiet, then a dead sensor, a flat battery or a cable someone drove over all read as all quiet. The house tells you everything is fine because it has stopped knowing anything. Where it matters, drive it from something that fails visible, or run a heartbeat. The TAP-5 has a heartbeat object monitoring its own bus connection and a tamper object that fires if the plate is pulled off the wall, which is the same principle applied to the keypad.

Why a light on the wall beats a notification on a phone

Mark Weiser and John Seely Brown at Xerox PARC wrote about calm technology in the mid nineties, defining it as technology that informs without demanding your focus or attention. Information should sit in your periphery and move to the centre only when it needs to.

A push notification is the opposite. It interrupts, it demands a decision, and by the fourth one you are swiping it away unread. That is not a discipline problem, it is what interruptive channels do to people.

A slow amber rotation on a plate in the passage is peripheral. Nothing is demanded. You walk past, your eye catches it, and it either means something right now or it does not. It works for a guest, for someone working in the house, for a family member who never installed anything. And it works when the internet does not, which around here is not hypothetical.

What to ask before you specify

How many independent notification objects does the range support, and are they genuinely separate from the button status objects. Are effect, colour, brightness and duration configurable per object. Is there a timeout mode and what is its ceiling. What is the priority order when two fire together. Can different keypads carry different notifications, because targeting is most of the value.

And one for architects and designers. If a plate is also an alert surface then its position is a sightline decision, not only a reach decision. The keypad in the passage you can see from the kitchen is doing a different job to the one behind the door. It is also a decent argument against stripping keypad count back to the bare minimum for the sake of clean walls, which is a conversation I have on most projects.

On a KNX job this capability is usually already sitting in hardware you were going to buy anyway. What it costs is an hour of thought at design stage about what the building should be able to tell you, and the restraint to keep that list very short.

If you are planning a build and want to work out what is worth putting on the wall, that is worth raising before the electrical layout is signed off. Not a sales pitch. Just a conversation about what the project needs.

Wayne KNX Logic wayne@knxlogic.co.za | 082 564 3982 | www.knxlogic.co.za