Network, power, security

A network cable pulled while the electrician is laying conduit anyway is practically free. Retrofitted, the same cable means: taking off skirting boards, gluing trunking, opening ceilings. So run a network socket and a power socket to every place where a screen might one day hang. Two sockets too many cost less than one too few.

One cable later replaces three wireless devices. Up to around a hundred metres a Cat 6 run needs nothing in between, and with PoE the power comes with it: about 15 watts under IEEE 802.3af, about 30 watts under 802.3at. That carries a player, a sensor, an access point – not a 55-inch display.

Screens do not belong on the same network as the till, and certainly not on the same one as guests. A separate VLAN costs your network administrator half an hour and spares you the question of whether the player in the shop window can see the accounts. I have taken over installations whose entrance totem was on the open visitor wifi, with the password displayed on a notice next to it.

Bandwidth is less often a problem than most people think, because a good player does not stream but pre-loads. The content is fetched overnight, sits on the device and plays from there. If the line fails during the day, the surface carries on – it just gets nothing new. It gets tight in distribution: twenty branches pulling the same video at once is noticeable. That is why updates belong at night, staggered across the sites.

At outdoor sites, mobile is often the more honest choice than a borrowed connection from the neighbouring building. And where an outage hurts, a mobile SIM as a second layer makes sense: it takes over when the fixed line drops out and sleeps otherwise.

A signage installation needs surprisingly few connections. As a rule it is enough that the players may phone outwards: fetch content, report status, ask whether there is anything new. Nothing has to be open from the outside in. Port forwarding to a screen on the sales floor needs a very good reason. Maintenance runs over VPN or the management interface, not over a permanently open remote support service with a password from the year the shop opened.

Software ages in operation: players get new versions, operating systems get security updates, certificates expire. The last of those is the classic – suddenly a browser message is standing in the shop window, because an expiry date was in nobody's calendar. Put a maintenance window in a night-time hour, update a test device first, then the rest in waves. A scheduled restart once a week is not a weakness but hygiene.

The most common power mistake is the most convenient one: the screen is on the same fuse as the shop-window lighting, and that goes off in the evening via a timer. Every evening the player is unplugged, every morning it restarts hard. After six months the memory card is damaged and nobody knows why. Give every surface its own permanently supplied feed.

The software should do the switching off, not the timer. Every usable control system knows a calendar, good displays accept commands via HDMI-CEC or RS-232 and shut their panel down themselves. The player stays awake and is there immediately in the morning. If you want to cut consumption, turn the brightness down at night; how to choose it in the first place is covered in the chapter on hardware.

Two things belong in the electrical planning and are gladly forgotten. First, wayfinding, displays on escape routes and emergency boards need an answer for a power cut – an uninterruptible supply or the rule that the printed board beside it takes over. Second, every fixed installation has to be connected and signed off by a qualified electrician. A cable running visibly to the socket may pass in an office; in a publicly accessible room it is a trip hazard.

Since the revision, the new data protection act, nDSG for short, applies in Switzerland. For screens that rarely means «forbidden» and almost always «say what you are doing». A surface that only displays collects nothing. It gets delicate as soon as a sensor is added.

Cameras and measuring sensors are permissible if they are proportionate and do not identify individuals. Cleanly built systems calculate inside the device: they count faces, roughly estimate dwell time or age group and discard the image immediately – what is stored is a number, never a face. Get that in writing and put a notice on the surface. A recording in which people are recognisable needs its own justification, a sign and a deletion deadline.

Two everyday cases I have to explain again and again. Anyone showing staff or customers in content needs their consent, preferably in writing – including for the team video somebody shot three years ago. And calling out names in waiting areas is a disclosure to everyone present; numbers or initials do the same job without half the waiting room learning who is sitting there for treatment.

Whatever runs on the screen belongs to somebody. Images from a stock library carry a licence, and that licence often distinguishes between editorial and advertising use, sometimes also between a screen inside the shop and a surface visible from the street. File the licence with every image; three years later nobody knows where the picture came from.

As soon as sound is added, SUISA comes into play. Music that is publicly audible is subject to royalties; for background music and audiovisual playback in businesses the joint tariffs apply, and which one applies depends on the surface, the use and the type of business. Settle that before the installation goes live. Many installations manage without sound anyway; why subtitles work better for passers-by is covered in the chapter on content.

Outdoors the municipality has a say. Screens and totems visible from public ground count as advertising and usually need a permit, regulated at municipal and cantonal level, with conditions on size, luminance and operating hours. Then there is glare: moving images in the field of view of drivers are judged strictly, often with minimum dwell times imposed. Ask the building authority early – a refusal after installation is the most expensive variant.

Plan for the bad day while the good one lasts. Three questions are enough: what happens if the internet is gone? What if the power is gone? And what does the customer see during those minutes?

Without internet a properly built player carries on, because the content sits locally. Only surfaces that live on live data are critical – departure times, queue numbers, occupancy plans. For those you need a fallback: the last valid information with a timestamp, or a calm standard page with the logo and opening hours. But not an error message in white on blue, right in the shop window.

After a power cut every device has to start up by itself. That is a setting in the screen and one in the player, and it is set wrongly surprisingly often. Check it deliberately: pull the plug, wait two minutes, plug it in, watch the clock. Anything that is not playing by itself after three minutes will not play on Sunday morning either.

That leaves the service chain. Who notices the outage – you, your employee, or monitoring that reports as soon as a device goes silent? A pre-configured replacement unit in the store cuts every fault down to one drive and one action.