Experts on the Internet of Things (IoT) believe that the planet-changing technology can only reach its full potential if it is based on wireless communications systems. Although a huge number of IoT nodes will certainly be battery-powered and connected wirelessly, there is still a large proportion of IoT systems that will benefit from the use of sensors that are connected via cables.
The issue for those responsible for designing and implementing IoT networks is which type of connector to use. There are many companies that offer a range of hardware-based connectors well suited to IoT applications but those searching for the best product are on the look-out for differentiating factors. Engineers want to know what makes a product unique, what benefits it provides and if the supplier has extensive knowledge of the product to support them in their applications.
Why the future isn’t all wireless
Many electronics hardware design engineers can be forgiven for not being fully aware of the range of modern compact connectors for IoT applications. The focus in recent years has leaned heavily towards wireless sensors but the reality is that hard-wired connectors are vitally important components within many IoT set-ups. Companies such as Farnell offer an extensive range of different connector solutions for these applications, particularly small connectors that are ideal for fitting to IoT sensors and nodes.
Hard-wired connections can be preferential for many reasons. For example, wired networking can often provide far more resilience and robustness in electrically noisy environments where reliable communications are essential without any interference. Similarly, in harsh environments it makes sense to make use of a wide range of industrial ethernet connectors that perform far better than wireless technology, including IP-rated connectors that provide protection against the ingress of water, dust and other elements. In such applications, connectors need to offer compact form-factors in order to minimise the circuit board real estate; standard RJ45 connectors are usually too large.
Examples of IoT-friendly connectors available today include HARTING’s RJ45 Industrial Ethernet data interfaces that incorporate features such as intuitive locking mechanisms, tool-free fast connection and thermoplastic or metal hoods and housings. Offering data transmission speeds of up to 10Gbit/s, these connectors tend to be rated to IP20, IP54, IP65 and IP67 while some also provide 4 x 48V/16A or 3 x 300V/16A, depending on the end-user’s requirements. Also available is HARTING’s ix industrial family of Ethernet interfaces that offer a miniaturised alternative to the RJ45 (requiring 70% less space). Referred to as a “small giant” for IoT applications, the ix industrial family consists of robust plug-in connectors that can produce Cat6a performance for 1Gbit/s to 10Gbit/s Ethernet. Ideal for harsh industrial environments, the units ensure safe data transmission with high EMC immunity to interference.
For some IoT applications, such as monitoring environmental conditions in the logistics sector, it may be necessary to use connectors that incorporate USB connections. Ideally suited to IoT networks, TE Connectivity’s universal connectors provide bi-directional, simultaneous signals for full speed (12Mbps) or low speed (1.5Mbps) used in USB systems. Easy to install, these TE systems comprise a single, four-position board-mount receptacle (BMR) and mating cable mount over-moulded plug. For flexibility and versatility in all types of USB applications, BMRs are available in standard, Type B, stacked, and side-by-side configurations. While Type-C USB connectors are small enough for use in mobile phones, micro USB 2.0 connectors are the smallest connectors of their kind that are capable of reliable and robust delivery of high-speed data. For transferring data 10 times faster than USB 2.0, design engineers can choose from a range of USB 3.0 connectors which support a data transfer rate of up to 5Gbit/s.
Another reason for using hard-wired sensors would be to meet the radio frequency (RF) challenges of environments such as noisy industrial installations. Although many IoT applications will not use external antennas, they can often prove ideal in these difficult RF environments where more reliable communications are required than could be provided by wireless sensors.
Even though Wi-Fi, Bluetooth and Zigbee cannot provide trouble-free connections over long distances, these technologies can enable fast and easy RF integration into connected systems, making them ideal for helping compact devices to provide high-performance internet and data connectivity. For example, Molex offers a range of 2.4GHz/5GHz and 900MHz ultra-thin ceramic and LDS/MID IoT antennas alongside their associated connectors. Molex also offers complete RF solutions for high frequency performance while delivering superior signal integrity, even in extremely demanding environments. Available in ultra-microminiature format (with a profile as low as 1.8mm) as well as larger RF units, Molex’s coaxial connectors and cable assemblies operate across a range of frequencies – from DC to 65GHz.
Different connectors for different needs
Of course, there are a myriad of connectors that offer a range of features suited to IoT applications and selecting the right connector is critical, not only in terms of delivering the required level of performance but also for keeping the footprint of IoT nodes and sensors to an absolute minimum.
Memory connectors
Although soldering memory direct to a board will minimise space it can also limit flexibility. With this in mind, many engineers choose memory modules, allowing them to expand the available memory should they need additional processing or other options. Both Molex and TE Connectivity offer excellent solutions in this area with their ranges of memory connectors and custom memory modules for server, storage and communication applications, again catering for different customer requirements.
Board-to-board connectors
Often, designers of IoT systems stack boards to allow flexibility (such as connecting different sensors to a standard communications board) and the free height board-to-board connectors produced by TE Connectivity are designed for such parallel board stacking applications. Ideal for downsizing applications, these versatile units use sub-miniature connectors and are suitable for a broad spectrum of interconnect uses.
The free height connectors offer a range of position sizes from 40 to 440 positions in contact pitches of 0.5mm, 0.6mm, 0.8mm and 1mm. By mating various combinations of vertical plug and receptacle housing heights, board-to-board stack heights from 4mm to 20mm can be achieved in 1mm increments. If further space savings are required, flexible board-to-board connections enable boards to be placed in any position that is best suited to minimising a device’s footprint.
At the same time, flexible cable connectors can offer extremely high connection density combined with small pitch sizes. To meet the ever-increasing demand for smaller, more reliable connections, Molex has developed a range of low-profile/high-density interconnects with pitches from 0.2mm to 2mm and a dual-contact design that increases connection reliability.
Power and data connectors
While some wireless sensors can deliver battery lives of up to 20 years, there are many IoT applications, particularly in the Industrial Internet of Things (IIoT), where having devices powered through cables can remove the burden of having to replace batteries. Being hard-wired also enables designers to incorporate higher-power processors and peripherals into their schemes.
Where power and data need to be combined, 2mm connectors are a standard option, such as those available from Samtec. The company’s pitch sockets, headers, terminals and board stackers are available in low-profile, elevated and high-density designs to connect multiple boards together. Among the various options available are vertical and right-angle/horizontal orientations as well as through-hole, surface mount, press-fit and pass-through terminations.
If an IoT design engineer is looking for a more compact form factor than the more conventional 2mm connectors, TE offers 1.5mm AMP CT connectors that are miniature wire-to-board interconnect solutions while Samtec offers 1.27 mm pitch board stacking socket and terminal strips. These rugged, low-cost products combine low profile with high-density and are available in a range of orientations and contact styles.
Ingress preventing connectors
As mentioned earlier, some applications need IoT devices that are resistant to water, or dust ingress and this requirement can be met with products such as HARTING’s lightweight Han® industrial connector families. These products can transmit both power and data and are ideal for linking heating or cooling units, fans, control terminals, lighting systems, drives and vibration conveyors. In outdoor installations the family offers protection against the ingress of dust and liquids up to IP65.
Configurable connectors
Of course, in the vast majority of IoT and IIoT applications, space is always a key factor. So, instead of working with standard off-the-shelf products that could include more contacts than required – and therefore take up space unnecessarily – it often makes sense to work with connectors that can be configured to meet the exact needs of an installation. That’s why Samtec, for example, offers the ability for design engineers to create exactly the connector options that they need through genuine, easy-to-use configurability.
Reliability and cost are key
At the same time, selecting the correct connector for a particular application will have reliability and cost among their most important criteria. With this in mind, TE Connectivity has developed its range of FASTON quick-connect terminals which includes low insertion force terminals, high temperature units and low-profile terminals. Available in insulated and uninsulated versions, straight and flag configurations and with various plating options, the terminals feature stress-relieved receptacles with positive lock for easy installation and secure retention.
Conclusion
It’s clear that even though there are countless advantages to wireless connectivity when designing IoT systems and installations, not least the ability to capture and share data across long distances at very low power, there is still a significant market for wired connectors and many state-of-the-art modules have been developed with these applications in mind.
Market-leading specialists have created a vast portfolio of different connector solutions for IoT applications and these can all be supplied and supported by Farnell, whatever the installation and the individual customer requirement. Small, reliable, powerful, robust and battery-free – those are the benefits offered by hardware-based connectivity systems which IoT designers need to be aware of when working on projects today and into the future.
Source: electronicsweekly
