In newer production lines, the first sensors and actuators that do not require cables or sliding contacts are becoming apparent. They can be used flexibly and enable completely new motion sequences in production processes. Until now, the most common reason for not using such solutions was an empty battery that brought production to a standstill. In the meantime, energy self-sufficient sensors and actuators have proven their worth. Energy harvesting modules convert kinetic energy, ambient light energy or heat differences into sufficient electrical energy to reliably send data packets over short-range radio connections of up to several hundred meters. A local energy storage system ensures trouble-free functionality for weeks in the event that not enough energy can be harvested from the environment. In addition to the EnOcean sub-GHz protocol, Bluetooth 5 and ZigBee 3.0 in the 2.4 GHz band are also available for networking the sensors and actuators.

ZigBee

The ZigBee Alliance seems to have learned from past mistakes. Version 3.0 of ZigBee is not only very popular with Amazon Echo, Philips Hue, Ikea Trädfri and Osram Lightfy, but also in the professional industry due to its specifications. A coordinated module combination from EnOcean is ideal for the use of energy harvesting with ZigBee. Like the radio stack, the radio unit is based on a semiconductor from Nordic Semiconductor.

Bluetooth and EnOcean

For simple P2P connections or for interaction with a smartphone, tablet or notebook, Bluetooth can also be used completely energy self-sufficiently. If you want more range or if the 2.4 GHz band is prohibited on the factory premises according to the frequency usage plan, you will find a tried and tested alternative in the EnOcean protocol from the EnOcean Alliance. The modules for energy conversion and radio communication from EnOcean are also used here. As a distributor, Rutronik works together with EnOcean GmbH and the EnOcean Alliance as well as with Nordic Semiconductor. As a result, developers receive cross-company support even for software-specific adaptations and more complex problems.

Full networking in the factory hall

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What is a perfect solution for connecting a sensor or actuator to a gateway, hub or edge computing unit - because it is maintenance-free and untethered - quickly reaches its limits in larger and more complex networks. Particularly in non-time-synchronized machine topologies, each radio node must always be on reception in order to receive incoming data packets and ensure that they are processed promptly. Permanent and more powerful energy suppliers must be used for this purpose. For stationary radio nodes
wired power sources are suitable, while airfuel charging technology is the mobile alternative for 'floating' wireless nodes, allowing considerably more freedom of movement than Qi charging technology. The best compromise for different requirements is usually the classic battery.

Many wireless standards - such as Bluetooth Mesh, WiFi Mesh and ANT BLAZE - have a history based on a star topology and have also been offering machine topologies for a few years now. ZigBee, Threat and some others were designed for full mesh communication right from the start. While WiFi mesh practically does not require a fixed power supply, all other mesh systems mentioned can be operated for months on a single battery charge.

In contrast to the domestic sector, where ZigBee controls LED lights, it is becoming apparent that unrouted Bluetooth mesh will become the measure of all things for industrial lighting systems in warehouses and production halls, open-plan offices and corridors. In contrast to the usual, targeted routing of data packets, the data flow here ensures particularly fast response and throughput times. Smartphones etc. can still be integrated into the network, which is another major advantage over other wireless standards that have to find their way to the IT equipment via a router.

Bluetooth Mesh can be seen as an intermediate layer that can theoretically be installed on all Bluetooth 4.0 hardware. However, due to the latest pricing from the Bluetooth Special Interest Group, it makes sense to use modern Bluetooth 5 or even better 5.2 hardware for new developments. Semiconductors with corresponding stacks are available from STMicroelectronics, Nordic Semiconductor, Toshiba, GoWIN and now, thanks to the Cypress takeover, also from Infineon. Those who prefer a solution with integrated high-frequency circuitry and certifications can choose from Bluetooth mesh modules from Insight SiP, Garmin, Panasonic, Murata, Telit, Fujitsu and Minew.

Out of sight, but closely connected

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Long-range radio is the method of choice for transshipment points such as logistics centers, railroad stations or ports. Among the technologies that use public and license-free ISM bands, LoRa has established itself in most Central European countries. France and the Netherlands in particular rely predominantly on Sigfox thanks to good network expansion.

However, a trend reversal began in 2019: The 4G categories Cat-M1 and Cat-NB1 were - depending on the region and application - very strongly accepted in some cases, and the first test phases have already gone into mass production. While LTE-M is suitable for tracking applications with cell switching, LTE-NB1 significantly undercuts the energy requirement once again.

In many countries, however, network expansion determines which low-power mobile technology is used. German mobile network providers are apparently concentrating on the metering market for the time being. As an installed electricity/gas/water meter does not move, there are no changes of mobile radio cells during a connection. Providers in other countries are focusing more on tracking applications for moving objects and have focused on expanding the M1 category. Most manufacturers of mobile radio modules support both networks. At Rutronik, for example, solutions from Telit, Nordic Semiconductor, Murata, Telic, Advantech and other franchise partners will soon be available.

Like 2G, 3G and conventional 4G modules, LTE-M1 transceivers are often combined with GNSS (Global Navigation Satellite System) in one housing, as they are aimed at monitoring the position and movement of containers, vehicles, high-value goods, people and animals. Here, the position must always be determined and transmitted via the mobile network. A few years ago, GPS was a practically unrivaled navigation system. With the Russian Glonass and the Chinese Beidou, GNSS alternatives came along, but they did not technically come close to the American system. The European Galileo made its breakthrough in 2019 and has been successfully used by millions of smartphones for some time now. In mid-2019, the decision was made to make higher positioning accuracy available free of charge, meaning that Galileo is now ahead of the GPS system in terms of the freely usable data of the L1 layer.

Galileo is also the only system to offer an authentication function. This makes it possible to ensure that the signals received actually originate from Galileo and not from a fake transmitting station. Galileo is also the only civilian system in democratic hands. Nevertheless, almost all users are best advised to use as many systems as possible in parallel. This is because the more satellites are used, the faster, more energy-efficient and more precise most modern multi-GNSS receivers can work. However, you should be prepared for future changes and be able to react if a system should fail. To change the settings in the firmware, you can use the NB1 or M1 modem in the module.

For applications that use GNSS with LoRa, Sigfox, Wi-Fi or Bluetooth, care must be taken to create a corresponding access option to the operating mode of the GNSS unit in the host controller. In most cases, an NMEA control command is sufficient to tell the receiver which systems it should use and which should be ignored. This remote functionality must always be implemented manually and, if the worst comes to the worst, can be disastrous for the application or even save lives and businesses.

Welcome to the 6th Wi-Fi generation

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All the information from the individual workstations comes together at process level. The data collected at the sensor is often not even processed at field level. In order to obtain information from it, at least an initial pre-processing of the data takes place here. For some applications, it is advantageous to be able to compare several incoming field data in parallel. This allows more complex pattern matching algorithms to be used, which not only compare against static patterns, but also have to constantly adapt their reference. More powerful x86-based systems are usually used for these and similar computationally intensive tasks.

Here too, there is a trend towards interconnection and towards wireless technologies at system level. The 6th Wi-Fi generation is not only faster than the previous generation, but is also characterized by better connection management of the participants, which is particularly beneficial in professional application scenarios.
Improved frequency allocation with regard to the 5G networks that will soon be created is a further argument.

System level: It all depends on the location

The choice of technology at system level depends heavily on the complexity and local conditions - such as the local size of the site or the company's frequency usage plan. For smaller and dynamic companies, Wi-Fi 6 may also be an option here, while larger companies with very static facilities are more likely to opt for a wired solution - for now. Because as soon as 5G is available and affordable, a rethink will take place here too.

Operating level: Here it may be the previous generation

When communicating between different plants, the information is previously compressed to such an extent that conventional LTE is absolutely sufficient in terms of data throughput and latency times - even for large international corporations. If you want to secure your wired Internet connection at the site, you can already use an LTE router to transmit the key figures that are important for operations via mobile communications.

While the lower LTE categories are usually used at field level, where individual sensor data is involved, category 6 or higher LTE is also permitted at operating level. Power consumption and the modem price play practically no role here, as the computers are always operated on the power grid and only very few LTE modems or LTE routers are used. Telit, Telic and Advantech offer solutions such as plug-in cards, external modems and routers. An individual complete solution connects them to a server from Intel or Asus, for example, equipped with an LTE modem from Telit and a Wi-Fi 6 card from Intel.

Further wireless trends in automation

Bernd Hantsche is Director Product Marketing Embedded & Wireless at Rutronik.

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NFC is another technology that is conquering industrial environments after end customer smartphones. The 13.56 MHz technology allows a secure exchange between active reader and passive transponder as well as between two active readers. Compatibility with almost all modern tablets and smartphones means that inexpensive standard hardware is available and expensive special devices - such as an RFID gun - can increasingly be dispensed with. In addition to the hardware costs, this also brings advantages in terms of software programming.

If you want to use RFID for longer distances or to scan several transponders at the same time, you must either use a different frequency or look at active systems. Here, the transponders are not powered by the reader's electromagnetic field and communicate via load feedback, but have their own power supply - usually battery or solar - and communicate in the 2.4 GHz band based on Bluetooth or a similar proprietary radio protocol.

Where neither hardwiring nor energy harvesting is an option and economical wireless connections such as Bluetooth Low Energy drain batteries too quickly, more and more industrial applications are relying on the ANT protocol. For example, the first time-of-flight sensors for high-precision distance measurement, which require very little energy, are expected shortly. ANT is also available ex works in most Android smartphones and, with multi-protocol SoC solutions, can also forward data traffic to Bluetooth networks without additional hardware costs.

When fast, predictable and stable solutions are needed

However, equipping devices, systems or machines with industrial communication can become a time and cost trap, depending on the level of experience. Radio technology always means that high-frequency circuit components are included, where the classic electrical engineering laws no longer always apply. As experienced high-frequency technicians do not grow on trees and the necessary measuring equipment costs around a year's salary, it is worth considering whether it makes sense to reinvent the wheel yourself. Expensive certifications, license costs and constant PCNs keep development departments permanently busy. Companies such as HMS have specialized in industrial communication and have portfolios ranging from semiconductor chips and modules to finished modems.