Electronics Insight
02. February 2022
Reading time: 8 Min.

Ethernet for Harsh Industrial Applications Requires Special Connectors

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Ethernet cables plugged into server

In modern mechanical and plant engineering, everything is about data transfer. Industry 4.0, Smart Factory and IoT are data-intensive concepts that demand efficient, uncomplicated data collection, transmission and processing.

Across the IT sector Ethernet in various standards such as EtherNet/IP, Profinet, EtherCAT or Ethernet Powerlink is the proven solution. It is estimated that over 60% of communication in industrial facilities runs via Ethernet. In computer networks and simple industrial environments, RJ45 interfaces are common – but is it possible or practical to connect a robot arm or a machine tool with such an interface? Should controllers and sensors in a wind turbine or in assembly lines communicate via such connectors designed for the IT world? Probably not.

Dust, moisture, vibrations and mechanical shocks demand tight and firmly attached connections. Here, Ethernet M12 circular connectors – specially developed for data transmission applications in the industrial sector – have become the standard.

Anyone wishing to equip a device with an industrial Ethernet interface will find plenty of components on the market. But simply soldering on a connector is far from being enough. Filtering must also be considered. At Würth Elektronik, we provide developers with a wide selection of inductive components. Within our LAN product range, that features over 350 different components, we’ve been offering filtered RJ45 sockets for many years.

However, why should LAN interfaces with integrated transformers and current-compensated chokes only be available for the RJ45 format? It’s a justified question that made us take action.

Through-hole contacts – but SMT mountable

With the M12 Ethernet socket WE-LANMX and the corresponding screw connector, we have a very compelling solution for industrial Ethernet robustness. We even managed to combine two contradictory requirements. For example, classic THT contacting delivers great advantages in applications that are exposed to vibrations. On the other hand, today PCBs for industrial electronics are also assembled with SMD components and soldered using a reflow process.

So how did we resolve this contradiction? Our solution is Through Hole Reflow (THR). With LCP (Liquid Crystal Polymer) housing material, the shape of the housing and the design of the pins, we have designed the THT connector in such a way that on one hand it can withstand the temperatures of the reflow oven and, on the other, ensures that heat also reaches the contacts effectively to create mechanically and electrically secure solder connections. In addition, so that WE-LANMX can also be assembled automatically, we supply the socket with a cap that can be easily picked and placed by an SMT placement machine using a proven vacuum nozzle.

But back to our original motivation for the new component: simple and space-saving placement of the connector by removing the need for inductive components mounted on the PCB. Two proven components were built into the M12 Ethernet connector, WE-STST and WE-CNSW. WE-STST, the “Super Tiny Signal Transformer” is particularly small with its 4532 design and is characterized by 1.5kV insulation voltage and 350µH OCL according to IEEE 802.3. We therefore also recommend this signal transformer as part of our SPE campaign. WE-CNSW is used as a current-compensated data line filter with high common-mode attenuation and a low influence on the useful signal.

Dust and waterproof

As mentioned previously, the argument in favor of M12 Ethernet interfaces is the sometimes harsh environmental conditions encountered in industrial environments. That’s why we offer the matching WE-LANMX screw connector. This is used to mount the interface in the housing, and this is where the screw thread of an M12 Ethernet cable comes into play. When plugged in, it guarantees a dustproof and waterproof connection that meets IP67 standards.

With our high-quality connector featuring integrated circuitry, we believe we have provided a compelling answer to the question of industrial Ethernet interfaces.