Sigfox - a company-specific solution from the French start-up of the same name founded in 2009 - is a so-called 'Low Power Wide Area Network' (LPWAN) that can bridge long ranges of up to 50 km with very low energy consumption. Based on this wireless protocol, Telemecanique Sensors - a Schneider Electric brand - released the 'OsiSense XIOT' in August after around two years of development. According to Andreas Gérard, Product Manager Sensors at Telemecanique Sensors, this cloud sensor works autonomously and independently of GSM networks for up to ten years thanks to its integrated lithium-ion battery. The effort otherwise required (PLC and GSM module) is no longer necessary, as the sensor - for example a pressure switch - is connected directly to the transmitter.

According to Gérard, "In addition to industrial applications, which are traditionally already very close to the IIoT, the advantages of the IIoT can be opened up for completely new areas of application, such as irrigation systems in agriculture, where pressure thresholds are monitored, or solutions for the waste disposal industry. Applications are also possible in water treatment, civil engineering and wherever the status of a limit switch on remote systems or machines needs to be monitored and it is also difficult to maintain a stable power supply, for example." If the status of the switching contact on the monitored component changes, the transmitter sends a message to the server via the network. This message is then sent to one or more recipients on a PC, tablet or smartphone to inform or warn the user of status changes.

When asked why Schneider Electric chose Sigfox and not LPWAN solutions from major telecommunications providers such as Vodafone or Telekom, Gérard replies: "At the moment, Sigfox simply has the advantage that we only have one partner, the provider of the same name, who takes care of network coverage in the relevant countries and with whom we were able to set up a contract quite easily. However, our roadmap also envisages developing something similar for LoRa - a corresponding solution is expected to be available at the end of 2019. In terms of technology, LoRa is ultimately almost identical to Sigfox. What makes life a little difficult for us today when it comes to LoRa is that, as you know, it is backed by a committee of traditional mobile network providers - and the circumstances are different in every country. That means you have to conclude contracts with several partners."

And what does Sigfox's network coverage actually look like? Gérard: "In 2016 - when we started with Sigfox - the coverage in Germany was still zero. Back then, we had installed our own Sigfox antenna at the trade fair for our proof-of-concept demo. Today, according to Sigfox, network coverage in Germany is already at 79%!" So far, so good - but what if there is no network? In this case, the user has three options: Either you conclude a contract directly with Sigfox to the effect that they install and operate a corresponding antenna on your own premises, for example. Or you can rent the antennas from Sigfox. As a third option, from 2019 there will be an antenna from Sigfox that looks like a DSL modem and can be purchased for a few hundred euros.

When asked about the costs for the actual communication or the transmitter itself, Gérard replies: "There are basically various contract options here. At Schneider, we initially opted for a maximum of 50 transmissions per day with a bandwidth of 12 bytes and a maximum of six events per hour. Sigfox itself allows up to 140 events per day. The transmitter's list price of 279 euros includes all communication for five years - including access to Schneider's cloud portal. The hardware without a Sigfox contract has a list price of 199 euros."

With its two digital inputs, the battery-powered transmitter allows the transmission of two binary signals or the connection of a maximum of two sensors without consuming any power of its own. However, according to Gérard, this is not the end of the story: "We are already developing further variants that work with any sensor - for example with inductive, optical or ultrasonic sensors - and also enable the transmission of analog signals. This then requires either a battery that needs to be charged from time to time or a permanent 24-volt supply nearby. Ultimately, this would open up many more fields of application for us. Last but not least, we will also offer something in terms of visualization and evaluation of the signals, for example in a SCADA system."