Simon Buddle argues that while KNX installations are inherently robust, if we add the internet to our control system infrastructure we should at least mitigate outages and access issues.
Last week I heard someone on the radio describe Google as part of the infrastructure of modern life. Indeed, the Internet is part of that infrastructure; it is the digital equivalent of roads, highways, and international flights, allowing you to be anywhere in the world almost instantly.
It’s true that 99% of the time, we don’t know where the digital information we’re currently searching for or viewing is located. Huge server farms exist all over the world, containing vast amounts of data that we can access 24/7. That is, until we experience an internet outage. While this is increasingly unlikely, it’s not impossible. And of course, there are simple backup solutions. A backup broadband connection “by line”, either wired or via 4/5G, can be effective in combating outages. Alternatively, the Starlink low-orbit satellite system also offers a viable solution.
The user interface
Just as many installers believe that all system functionality should be present on the KNX bus, providing the customer with a robust system that relies solely on bus wiring, actuators and keypads, the same logic could be applied to user interfaces or applications. Most, if not all, customers will have a user interface of some description, i.e. a device that brings together all facets of the system on a single unified device. This device will most likely offer additional controls such as timers, scene recording options and/or occupancy simulation.
Although the application can be considered an integral part of a KNX system today, it usually requires more than just the KNX bus to make it work. At a minimum, we will need a data network, often with PoE (Power over Ethernet) as the physical link layer if it is a static display that has been installed as part of the building structure.
Smartphones and tablets will require Wi-Fi and/or internet. While we think of this as part of the infrastructure, it is a digital domain that is largely out of our control. Young people today often view their lives as both a digital and a real-world existence. There has been much debate about children’s screen time and the negative impact it can have – this is not relevant to this article, it is just further evidence of our internet addiction. We have control over the Wi-Fi in our homes, but not the internet.
Should we rely on Internet access as part of a control system?
The answer is clearly “no”. We control multiple systems through a single integrated platform and while the internet is ubiquitous, it is not something to be relied upon. Likewise, most people are annoyed when it doesn’t work. Think about the players. From a system design perspective, this raises some important questions. There is no right or wrong answer here, it is simply a matter of appreciating the implications and being aware of them on the part of our customers.
Access the control application
Starting with the physical location of the application, where are the zeros and ones kept? If they are in the cloud, we will need working internet. This is fine when the customer moves in, but during commissioning this can be a problem. So it might be better to install everything on the shop floor. If the application is on a product at home, we are ready to go once the data network and Wi-Fi are up and running. This is usually part of our remit from an installation and commissioning perspective, but not always. If not, we need to allow some time to discuss and agree our requirements with the IT/data company. It might be better to have a separate VLAN for our kit.
If the application resides inside the property, then we need to consider how the end user connects to it from outside the home. Secure remote access is now a common feature with many manufacturers, but it still needs to be configured and tested. It obviously requires a router and an internet connection. For many customers, Apple HomeKit, Google Home or Alexa are the user interface of choice. For this, you will need a KNX bridge such as the 1Home Bridge, Atios KNX Bridge or similar.
Conclusion
Although it is easy to forget exactly where software/applications are located these days, it is our job to know this clearly and to be able to convey this to our customers. There are no right or wrong things, just nuances that can sway a customer in one direction or another. Our skill is to inform, discuss and install accordingly. It is up to the customer to decide which of the options suits them best. The KNX world offers so many options that we are always able to offer a solution. No other product set can do this.
Simon Buddle CEng MIET, is a consultant for Future Ready Homes, specialising in the design of BMS and ELV service systems.