The Internet of Things (IoT) began to reach broad feasibility about 10 years ago with the introduction of powerful and affordable SoCs (System-on-Chip) with integrated Wi-Fi and Bluetooth. Over the years, the quantity and, above all, the quality of the available development frameworks has increased noticeably, so that today's available IoT device platforms can be used to realise sophisticated applications in the industrial sector.
At the same time, there is a wide range of development boards for every conceivable use case, starting with monitoring environmental conditions, recording medical parameters, providing intuitive HMIs (Human Machine Interfaces), audio processing/voice recognition and image analysis. This offering is rounded off by a range of miniaturised and easily controllable sensors, some of which are a by-product of smartphone development. This gives companies that were previously unable to overcome the barrier of entry into the market of developing their own hardware the opportunity to offer innovative products with a combination of hardware and software.
There are of course several hurdles to overcome on the way to becoming an integrated provider of hardware and software. While software requirements are a safe bet for us, there is a range of technical and legal framework conditions to consider when selecting the hardware.
Technical & legal frameworks
An essential point are the environmental conditions at the planned location of use of the IoT device. These determine the effort that has to be made to protect and increase the reliability of the devices.
Particularly relevant when the units are installed for a longer period of time, the ability to maintain and repair them is crucial. Fault analysis and the replacement of defective components can be optimised to save time and costs.
In the field of power supply, there is a broad choice for the various application scenarios. In most cases, data communication causes a large part of the energy consumption, while modern sensors manage with very low currents. Creative solutions may be required at this point, depending on the amount of data and communication cycles as well as network availability and device location.
A computer with sensors only becomes an IoT device through the network connection. This ensures that the collected data reaches the backend of the overall application with only a short time delay. Here, too, there are different technologies with specific advantages and disadvantages.
An network connection enables the implementation of remote software updates. This allows bug fixes as well as new functions to be made available quickly and cost-effectively on the IoT devices.
Last but not least, security**** and the area of legal requirements around product liability and certification must also be considered.
Environmental conditions
Unlike in a protected laboratory area, industrial environments tend to have harsh environmental conditions. Temperatures follow the course of the seasons. High humidity causes leakage currents, attacks materials and dampens the range of radio signals. Machines cause constant vibrations. Equipment has to "endure" one or the other (accidental) mechanical impact such as shock, impact and especially cable pulling. These challenges can be solved by using enclosures with the appropriate degree of protection (IPxx) and impact resistance (IKxx), as well as stable cable fixtures and strain relief.
Maintenance and repair capability
As early as in the design phase, one should think about the maintainability and repairability of the units. After installation, the units are sometimes located in areas that are difficult to reach. Device components and cabling are no longer easily replaceable due to the way they are installed. A modular design (cables, plug-in subcomponents) can considerably reduce the effort required for repair. A prerequisite is the availability of the most comprehensive fault diagnosis possible at the installation site. The use of an integrated display has proven to be quite helpful. This makes it possible to set up the units at the installation location, and many problems can later be narrowed down and repaired on site by technicians without additional equipment and extensive training. Relevant parameters are the strength of the signal of network connections, the connection status to the backend and operating figures of connected sensors. In addition, we have integrated a maintenance console into our IoT solutions that can be accessed via Wi-Fi, which can be used to change all configuration parameters and provides information about the current status of the running software components (e.g. log messages, data rates, processor utilisation).
Power supply
A stable power supply is the basis for reliable IoT devices. If mains voltage can be laid close to the sensor with reasonable effort, the use of a power supply unit has proven successful. Mobile sensors can be powered by batteries or rechargeable batteries (with very low power consumption), solar cells (only outdoors) or small generators. It should be noted that devices with mobile or Wi-Fi communication have short-term current peaks that can be many times the normal current consumption. If the power supply cannot provide this power, the integrated brownout detection leads to a controlled shutdown of the processor (and, depending on the configuration, to a restart when sufficient voltage is applied again) to prevent undesired misbehaviour. Unexpected restarts do not always indicate software errors, but sometimes a proper power supply can do the trick.
Network connection
The network connection of the IoT devices can be implemented via different technologies. If the network coverage permits it, the most independent solution is the use of a built-in mobile radio connection (beware of metal roofs and wall cladding as well as larger metal installations). However, it is quite cost-intensive in the long run for large amounts of data or sensors.
For larger data rates and distances inside buildings, the use of Wi-Fi is recommended. For this, there must be no metal parts between the device antenna and the access point that could interfere with the radio connection. With PCB antennas (integrated on the circuit board of the device), the distance should be less than 30 metres. If there is a large number of devices, bottlenecks will occur in the WLAN network; in this case, Bluetooth can be used.
Bluetooth offers a lower range and data rate and thus less interference with other devices. Poor network coverage can be compensated for by installing additional gateways. The main advantage of Bluetooth is its low energy consumption, which opens up alternative power supply options.
Last but not least, a wired connection via Ethernet is an interesting option, especially if the data rate and stability of the connection are paramount. The disadvantage is the high installation effort.
With all variants except mobile radio connection, IoT devices usually need to be integrated into the company network. Due to high security requirements for the production-relevant IT infrastructure, access e.g. to a cloud provider via the internet is not easily possible. In addition to a necessary activation of the devices for selected target addresses, access to the internet is often via a proxy where only communication via HTTP/HTTPS ports is allowed. The MQTT protocol, which is popular in the IoT sector, cannot communicate directly via these ports, both unencrypted and with TLS encryption. As an alternative, the encrypted MQTT connection can be tunnelled via WebSockets.
Software updates
In practical use, the updateability of the devices is an important criterion. The more complex the software of an IoT device, the more likely it is that bug fixes or function extensions will be needed later. However, updates via USB cable are very time-consuming because all devices must be physically reached. A remedy is a remote update feature (FOTA = Flash Over The Air), whereby large numbers of devices can be equipped with new software versions relatively easily via the internet. To ensure that only authorised firmware is installed, the software package must be digitally signed so that it is accepted by the device.
Security
As IoT devices are not usually housed in a highly secure data centre, there is a risk of unauthorised physical access. On the one hand, this is a security issue, as communication keys and passwords could be tapped, which in turn can be used to attack the network infrastructure. Additionally, the intellectual property of the installed software needs to be protected.
The solution is to establish device encryption that ensures that attackers only capture worthless data rubbish. For this purpose, after the initial flashing of the device, the flash memory (code and data) is encrypted on a hardware basis. The key is device-specific, cannot be read out and cannot be changed (stored in so-called eFuses). Since encryption cannot be switched off, reading of usable information from the flash memory is prevented.
Legal requirements
Even if you only install bought-in development boards in their own housing, you are considered to be the manufacturer or distributor of these devices and are therefore responsible for product safety. The purpose of the regulations on product safety is to ensure an appropriate level of protection for consumers and commercial users. In the case of hardware assembled from already certified components, the Product Safety Act and the CE Directives need to be considered.
The use of existing legislation provides good guidance for the development of new products, reduces liability risks and is a prerequisite for the sale of products in certain markets and for product liability insurance. However, safety requirements incurr additional expenses and restrictions in product design as well as a reduction in the speed of innovation.
Conclusion
The availability of mature IoT platforms forms the basis for a number of new application scenarios in the industrial sector that were not economically feasible a few years ago. Now that control technology has already been automated to the greatest possible extent, recording of the condition of technical systems is coming to the fore as the basis for maintenance planning and forecasting. staff can thus be relieved of routine inspection rounds and measurements and concentrate entirely on maintenance.
For companies that are well positioned in the field of software development and data science, this provides an outstanding opportunity to offer problem-specific solutions for Industry 4.0 "from a single source" if the necessary IoT sensors can also be supplied. This can be achieved with appropriate partners, but is also possible independently, taking into account certain technical and legal framework conditions.
