Being relatively less costly, wireless sensor network (WSN) has allowed businesses to deploy hundreds or even thousands of sensing nodes within their facilities, creating IIoT systems, says Mark Patrick.

 

Technology is constantly changing and improving the world we live in. Many believe that a combination of the Internet, cloud computing, data analytics and the creation of the Industrial Internet of Things (IIoT) have moved us to the point where we are entering the fourth industrial revolution, sometimes termed Industry 4.0. Monitoring our industrial infrastructure including power plants, railways, gas pipelines and refineries has always been important and possible with wired technology, but this is expected to advance rapidly with the advent of wireless sensor networks (WSNs).

 

Through augmenting data from the control system with additional data from IIoT nodes, businesses can enhance the dataset available to them which, in turn, will enable them to optimise their entire business models. Predictive maintenance is one area that will benefit, monitoring wear on important equipment and predicting the need for preventive maintenance that will reduce repair bills and avoid the significant costs associated with unplanned downtime. It can also control costs, as maintenance is only carried out when needed, which may be less than the normal schedule. This is of particular benefit when the equipment is remotely located or otherwise hard to access.

 

Last year (2018) there were around 1 billion WSN chipsets shipped, although forecasts from On World estimate this will more than triple to 3.4 billion by 2023. At the moment shipments are dominated (around 90 per cent) by technologies including Bluetooth, 802.15.4 and some proprietary protocols. However, things are changing and low-power wide area (LPWA) technologies such as Sigfox, LoRa and NB-IoT are increasing at a much faster rate, eventually representing a much larger proportion of the market. The On World report goes on to predict that revenues for WSN hardware and the associated services will increase beyond $13 billion by 2023.

 

The nerve center of the IIoT

In the industrial sector, security and reliability are paramount and cost often takes a back seat, especially as the smooth and efficient operation of facilities is critical. If these sites do not operate well then the ensuing failures, delays or accidents will cost far more in terms of revenue loss or industrial accidents, which could even be fatal. Technological improvements including miniaturisation, improved embedded computing, better wireless comms and improved power efficiency and management have led to highly functional yet ultra-low-power wireless sensor nodes that can function on a single button cell for more than a year, even in harsh environments.

 

As WSN technology is relatively low cost, this has allowed businesses to deploy hundreds or even thousands of sensing nodes within their facilities, creating IIoT systems that, to an extent, mimic the complex human nervous system. Through the implementation of multiple wireless protocols, these extensive networks are able to deliver reliable ecosystems that include large numbers of sensing nodes, repeaters and gateways that enable the redundancies necessary for reliable and robust Industry 4.0 implementations. 

 

IIoT wireless protocol hardware support 

These systems have to exist in environments that are not necessarily friendly to technology. The size of facilities is a challenge, as is the presence of concrete and metal in the physical building structures. Existing electrical and electronic equipment, including switchgear, will all produce electromagnetic interference that can impact the wireless communication of IIoT nodes. Considering all of these factors allows designers to decide on the appropriate type of IIoT node to implement, as well as the wireless protocol to provide the all-important connectivity. Options include Bluetooth Low Energy (BLE), WirelessHART, ISA-100.11a and Zigbee.

 

The 2.4GHz transceiver modules from Microchip deliver extended battery life through their low-current reception abilities. The modules incorporate IEEE 802.11 firmware with a simple-to-implement API driver that connects to Microchip’s no-cost TCP/IP stack as well as the often-used PIC microcontroller units (MCUs). The modules simplify the design task (and reduce costs) as there is no requirement to develop RF circuitry from a blank sheet of paper or to follow the agency approval path. As an example, the RN1810 module offers an onboard TCP/IP networking stack, power management, RF power amplifier, cryptographic accelerator, 2.4GHz transceiver and real-time clock.

 

The PAN9026 module from Panasonic combines Bluetooth BDR/EDR/LE with IEEE 802.11a/b/g/n support that together deliver the flexibility necessary for home gateways and IIoT applications. Simultaneous operation in 2.4GHz and 5GHz is made possible via dynamic rapid channel switching (DRCS). This dual-mode, independent operation allows data rates of 150Mbps to be reached while maintaining low-power operation requiring just 400mA when transmitting and 70mA when receiving. Through the provision of inbuilt power management, a powerful dual-core CPU, high-speed data interfaces and 802.11i-based security, the module has all that is required for fast and reliable 

IIoT solutions.

 

Intelligent solutions for WSN

The Ember EM35x series from Silicon Labs is based around highly integrated system-on-chip (SoC) devices that include features such as a 2.4GHz, IEEE 802.15.4-2003- compliant transceiver, 32-bit ARM Cortex-M3 microprocessor, Flash memory and RAM, plus several peripheral devices that are useful in Zigbee-based designs. The efficient architecture of the transceiver section provides more than 15dB of dynamic range over and above the requirements of IEEE 802.15.4-2003. Advanced and integrated channel filtering allows the device to 

coexist with other 2.4GHz standards, including Bluetooth and IEEE 802.11-2007.

 

The ultra-low power, high-performance wireless JN5148-001 MCUs from NXP Semiconductors are specifically aimed at Zigbee PRO applications. The enhanced 32-bit RISC processor brings a number of benefits including variable width instructions that offer high coding efficiency. There is also a multi-stage instruction pipeline and user-definable clock speeds to assist with power conservation. Alongside multiple analog and digital peripheral devices, these MCUs also incorporate 128kB of ROM and RAM and a 2.4GHz IEEE 802.15.4-compliant transceiver. The provision of significant memory resources allows the running of an application or network stack as well as the ability to function in a co-processor mode.

 

Application-specific inbuilt peripherals include pulse counters that are ideal for use in automatic meter reading (AMR) systems as well as a unique time-of-flight (ToF) ranging engine that provides accurate location services over WSNs. Even with all of this inbuilt functionality, the operating current is less than 18mA, allowing the MCUs to be powered from a coin cell.Other SoC solutions include Texas Instruments’ CC2530, CC2531 and CC2533 devices that are intended for use in 802.15.4, Zigbee and RF4CE-based systems. Based around an 8051 MCU, they incorporate a high-performance RF transceiver, 8kB of RAM and programmable Flash memory. As an example, the CC2531 enables USB dongles or network nodes with USB upgradability to be developed at low cost. In addition, a range of operating modes allow for low-power operation and these modes can be switched rapidly, further enhancing the energy saving. Another device, the CC2530 is suited to Zigbee PRO applications, due to the provision of up to 256kB of Flash memory. All CC2530 devices with 64kB or more of Flash support the RemoTI stack for Zigbee RF4CE, which is the first Zigbee RF4CE-compliant protocol stack. The devices with more memory also support in-system reprogramming via on-chip over-the-air download. The final device in the series, the CC2533, offers up to 96kB of programmable Flash memory and 6kB of RAM.

 

Available from the Dust Networks product group of Analog Devices, the SmartMesh IP wireless solutions comprise a range of embedded chips and pre-certified PCB modules. The modules are provided with fully developed, field-proven, intelligent wireless mesh networking software. SmartMesh-based WSNs can deliver data reliability upward of 99.999 per cent, even when coupled with ultra-low-power, secure wireless communication systems, allowing sensors to be placed in challenging IIoT environments. The SmartMesh nodes are all based around the Eterna IEEE 802.15.4e SoC that includes Analog Devices’ fully integrated and low power 2.4GHz radio. Also included in 

the SoC is an ARM Cortex-M3 32-bit microprocessor that runs the necessary SmartMesh networking software.

 

The technology to support Industry 4.0, especially with regard to WSN, is developing rapidly and is now widely available. Both discrete (IC) and module-based solutions are available that can meet the demanding needs of the IIoT environment while delivering low-power operation 

and the security needed to ward off an increasing number of threat types. These advances are sure to lead to increased automation on a global scale, with all of the benefits that implies.

 

About the author:

Mark Patrick is the Supplier & Technical Marketing Manager EMEA at Mouser Electronics.