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Sensor Networking in Legacy Industrial Automation Facilities with a LoRaWAN Multiprotocol Gateway

By Bill Giovino

Contributed By Digi-Key's North American Editors

As the Industrial Internet of Things (IIoT) continues to expand, so too are the types of networking technologies that are being used to connect different systems. For wired networking, Ethernet (and its Industrial Ethernet variant) is the most common interface as it is versatile and can run a number of different protocols. For wireless high-speed data, Wi-Fi has become the standard for fast and reliable networking, while Bluetooth is used for some sensors and to configure equipment.

However, Bluetooth operates in the 2.45 gigahertz (GHz) band, while Wi-Fi operates in both the 2.45 GHz and 5 GHz band. As a result, the heavy walls used in legacy building construction can significantly reduce the range of Wi-Fi and Bluetooth transmissions, compared to radios like LoRaWAN that operate in the sub-GHz bands. This compromises sensor connectivity and so adds to the cost as more access or aggregation points need to be deployed across a facility to prevent devices from losing a wireless connection.

This article explains why it may be necessary to add LoRaWAN sensor connectivity in industrial automation facilities that already have Wi-Fi and Bluetooth. It examines the advantages of LoRaWAN in older buildings and legacy environments that must be adapted for industrial automation and building management. It then looks at two LoRaWAN gateways from Multi-Tech Systems that can easily manage Wi-Fi data networking, LoRaWAN sensor connectivity, and Bluetooth connectivity, while maintaining backwards compatibility.

How to add wireless connectivity in older buildings

The expansion of the IIoT has resulted in some legacy buildings being tasked for IIoT networking. However, these older buildings were constructed years before anyone was concerned about transmitting data wirelessly across the building. Walls, floors, and ceilings often have steel mesh, rebar, and heavy steel beams for reinforcement that effectively block high frequency radio signals, blocking network access to some equipment.

In some cases, connectivity through a wall may be adequate until a forklift or other heavy equipment is placed near the wall and connectivity is temporarily blocked. This presents a problem for high frequency wireless protocols like Wi-Fi and Bluetooth. Diagnosing these intermittent borderline connectivity situations is a network technician’s nightmare.

As a result, these buildings can require additional routers, network switches, and gateways in the facilities. This increases the complexity of the network while adding cost, maintenance, and interoperability concerns.

The situation is especially problematic for remote sensors, which can be located hundreds of feet away from the gateway or router. However, some sensors such as environmental sensors do not need to constantly transmit their status over a high-speed wireless network and can easily use sub-GHz frequencies without any network bottlenecks or race conditions.

For these situations, the sub-GHz low-power LoRaWAN wireless protocol is a reliable option. LoRaWAN transmits over the frequency range of 902 to 928 megahertz (MHz) in the USA and over 863 to 870 MHz in the EU. It targets low-power, low data rate sensors that do not need constant data connections. More importantly, LoRaWAN’s lower operating frequency bands make it appropriate for older buildings with thick reinforced walls, as the transmitted signal easily passes through wood, drywall, concrete, and steel.

However, if the industrial facility is using Wi-Fi, Bluetooth, and LoRaWAN, it is important to integrate all three protocols in a way that ensures reliability and interoperability, while lowering maintenance costs.

IIoT LoRaWAN configuration

Typically, Wi-Fi signals are connected to an industrial facility’s central hub through a network switch or router, which translates the data over wired Ethernet. This translation is relatively easy because Wi-Fi and Ethernet are compatible protocols. However, LoRaWAN is not compatible with Ethernet, so the data cannot be simply passed off. Instead, in order for LoRaWAN data to reach the central hub, the wireless LoRaWAN data must first be received by a compatible gateway. A LoRaWAN compatible gateway is configured to forward the data over a backhaul connection to a Windows or Linux central hub running the LoRaWAN Network Server (LNS) application. The LNS processes the data and exposes it to the hub’s operating system by application programming interfaces (APIs) available to the application software.

A LoRaWAN multiprotocol gateway designed for rugged industrial facilities is the MTCDT-247A-915-US-EU-GB multiprotocol gateway from Multi-Tech Systems (Figure 1). The gateway targets industrial environments and can operate over temperatures of -30°C to +70°C, and at up to 90% relative humidity (non-condensing).

The MTCDT-247A-915-US-EU-GB is configured for the LoRaWAN USA frequencies and cannot be used in other regions. The MTCDT-247A-915-US-EU-GB supports Wi-Fi, Bluetooth, and LoRaWAN.

Image of MTCDT-247A-915-US-EU-GB gateway from Multi-Tech SystemsFigure 1: The MTCDT-247A-915-US-EU-GB gateway from Multi-Tech Systems is a Wi-Fi router and LoRaWAN gateway for industrial environments. It operates over USA LoRaWAN frequencies of 902 to 928 MHz and also supports Bluetooth connectivity. (Image source: Multi-Tech Systems)

This Conduit gateway supports LoRaWAN networking in the USA 915 MHz band. The gateway uses a browser-based interface for configuring the LoRaWAN packet forwarder to point to the LNS. LoRaWAN sensors located inside the industrial facility can easily connect to a Conduit gateway many hundreds of feet away, even through the steel reinforced concrete walls and floors found in older buildings. However, even modern buildings will have dark spots—locations where wireless signals do not reach. This is always an issue for large buildings and cannot be avoided. For this reason, it is recommended to have at least two LoRaWAN gateways to ensure complete coverage. The LNS application resolves any issues when receiving identical data packets from two or more Conduit gateways.

The browser interface can also be used to configure the Wi-Fi access point. The MTCDT-247A-915-US-EU-GB can provide Wi-Fi access points for an industrial facility at 2.45 GHz and 5 GHz for 802.11a/b/g/n protocols. A Wi-Fi antenna is included with the gateway.

The browser interface can also configure the Bluetooth access point for connection to compatible Bluetooth devices. Bluetooth Classic is supported for always-on high data rate Bluetooth devices. For battery-powered Bluetooth devices such as tablets, laptops, and some sensors, Bluetooth LE 4.1 is supported.

The networking connection and backhaul to the main server is by wired 10/100BaseT Ethernet from an RJ45 jack on the back.

The MTCDT-247A-915-US-EU-GB also supports the Global Navigation Satellite System (GNSS). This can be used for global positioning, but more importantly GNSS provides an accurate time base for LoRaWAN packet time stamps, which is required by the LoRaWAN standard to ensure message synchronization.

The MTCDT-247A-915-US-EU-GB combines USA LoRaWAN, Wi-Fi, and Bluetooth hub connectivity in one gateway, providing a central point of maintenance for all three wireless protocols and simplifying network connectivity. The gateway is designed so that the three protocols do not interfere with each other.

For use in the EU, Multi-Tech Systems supplies the MTCDT-L4E1-247A-868-EU-GB gateway, which is identical to the U.S. version except that it is operates in the EU 868 MHz LoRaWAN band, from of 863 to 870 MHz, and additionally supports 4G-LTE cellular connectivity for the backhaul. For cost-effective operation in areas not served by modern cellular standards, the gateway can also send data over 3G-HSPA+ and 2G-GPRS networks. Multi-Tech Systems specifies that this gateway is compatible with all EU cellular networks.

The MTCDT-L4E1-247A-868-EU-GB comes with a selection of adapters compatible with most EU power outlets. It also includes a Wi-Fi antenna, a GNSS antenna, and two cellular antennas (Figure 2).

Image of Multi-Tech Systems MTCDT-247A-915-US-EU-GB gatewayFigure 2: The Multi-Tech Systems MTCDT-247A-915-US-EU-GB gateway supports LoRaWAN connectivity in EU countries in the 868 MHz band, while also supporting 4G-LTE cellular backhaul connectivity. It comes with a selection of European AC power adapters that are compatible with most countries. (Image source: Multi-Tech Systems)

To send LoRaWAN data to an LNS over a 4G-LTE network, each gateway requires a standard SIM card containing the wireless network, telephone number, and subscriber information.

The MTCDT-L4E1-247A-868-EU-GB has a SIM card holder on the front of the unit behind the nameplate. To protect the SIM card from casual replacement by malicious actors, a screw secures the nameplate in place (Figure 3). For additional security the gateway should be kept in a locked location that is inaccessible to unauthorized users. It’s important to ensure that the location is not surrounded by a metal enclosure, which would hinder Bluetooth and Wi-Fi signals.

Image of Multi-Tech MTCDT-L4E1-247A-868-EU-GB gateway SIM card portFigure 3: The MTCDT-L4E1-247A-868-EU-GB gateway has a SIM card port accessible by removing the nameplate, which is secured by a small screw. (Image source: Multi-Tech Systems)

Each Multi-Tech Systems Conduit LoRaWAN gateway that supports a 4G-LTE backhaul will require the purchase of a SIM card with an appropriate data plan from a cellular carrier. A SIM card and cellular data plan for a Conduit gateway can be conveniently purchased from Digi-Key. Plans are available with data capacities from 300 kilobytes (Kbytes) up to 5 gigabytes (Gbytes) per month.

The Multi-Tech Systems Conduit gateway provides one easy central point of access for four wireless connectivity protocols plus GNSS, all in one unit. For maintenance personnel this allows all wireless networks to be easily configured from one location, saving time and increasing reliability. This also eliminates conflicts that might occur if separate routers and gateways were used.

Conclusion

Wireless networking is increasingly useful for industrial automation as plants and factories adopt IIoT practices. For these applications, there is already a rich ecosystem of devices supporting Wi-Fi and Bluetooth for a variety of applications, often operating across different frequency bands. As described, adding LoRaWAN sensor connectivity with its sub-GHz operation in industrial automation facilities that already have Wi-Fi and Bluetooth can improve reliability, especially in older facilities with steel reinforced walls. Using one gateway that supports all these protocols saves time and configuration costs, while improving compatibility and reliability.

Disclaimer: The opinions, beliefs, and viewpoints expressed by the various authors and/or forum participants on this website do not necessarily reflect the opinions, beliefs, and viewpoints of Digi-Key Electronics or official policies of Digi-Key Electronics.

About this author

Bill Giovino

Bill Giovino is an Electronics Engineer with a BSEE from Syracuse University, and is one of the few people to successfully jump from design engineer, to field applications engineer, to technology marketing.

For over 25 years Bill has enjoyed promoting new technologies in front of technical and non-technical audiences alike for many companies including STMicroelectronics, Intel, and Maxim Integrated. While at STMicroelectronics, Bill helped spearhead the company’s early successes in the microcontroller industry. At Infineon Bill orchestrated the company’s first microcontroller design wins in U.S. automotive. As a marketing consultant for his company CPU Technologies, Bill has helped many companies turn underperforming products into success stories.

Bill was an early adopter of the Internet of Things, including putting the first full TCP/IP stack on a microcontroller. Bill is devoted to the message of “Sales Through Education” and the increasing importance of clear, well written communications in promoting products online. He is moderator of the popular LinkedIn Semiconductor Sales & Marketing Group and speaks B2E fluently.

About this publisher

Digi-Key's North American Editors