Creating high performance and secure Ethernet networks are top priorities for designers of any commercial or industrial systems using digital connectivity. Because Ethernet is so commonly deployed in many different settings, it can be tempting to select consumer-grade devices, even though far more capable hardware is available and warranted. Cost pressures often increase because professional-grade solutions like managed switches are relatively expensive, with much time required for complex configuration.

But another option is available in the form of industrialized unmanaged Ethernet switches, which incorporate the key performance features of managed switches in an easy-to-deploy form factor. This article identifies top features designers should look for, and it shows how the right unmanaged switches are easily employed in any Ethernet applications to deliver robust connectivity.

Digital need for speed

Many digital system applications have largely been standardized on Ethernet communications, due to the speed and bandwidth capabilities, not to mention the economies of scale based on such a massively deployed technology.

Nearly all types of electronic devices are produced with a level of intelligence so they can be linked to each other and to supervisory control and monitoring systems. Industrial internet of things (IIoT) initiatives are underway with many end users in an effort to gather as much data as possible from all sources, in support of remote monitoring and control—further driving the need for high-speed Ethernet communications.

This is true for diverse industries and applications—such as building automation, municipal traffic control, power utilities, water/wastewater treatment, processing industries—along with just about any type of manufacturing machinery or equipment. Supervisory devices may be dedicated controllers, programmable logic controllers (PLCs), hardware human-machine interfaces (HMIs), or locally installed PCs. Field devices range from IIoT sensors to intelligent devices, like RFID readers or process analyzers.

Basically, anywhere multiple Ethernet devices are to be connected, a switch is needed. Typically, 4-port switches are the smallest available, but many users find that the increasing number of field devices and the need for a user connection port push them into higher port counts. Many of these users find an 8-port switch to be an excellent balance between size and capacity.

Because so many commercial and industrial applications are largely mission-critical, any downtime due to network problems is unacceptable. The next step is to pick a model able to deliver the required performance and reliability, even in challenging physical locations.

Unmanaged versus managed

A basic unmanaged Ethernet switch is basically plug-and-play and typically requires no user configuration. Each port will auto-configure to match the connected device, and the switch will build MAC address tables to forward traffic with some level of intelligence. There are almost no security provisions. Unmanaged switches are very economical, and often considered for small networks where changes will not be needed, and average performance is acceptable.

Managed Ethernet switches are usually required if users want to increase communication speeds, minimize traffic and network loading, and improve network security. Each of these characteristics is desirable for many types of commercial and industrial installations, where equipment, devices, and digital services must reliably operate around the clock.

Unfortunately, managed switches usually must be configured by personnel with significant IT training, and these configurations must be maintained among all the switches on the network. The task can be daunting for users who simply want high-quality connectivity. Therefore, managed switches originally carried larger port counts and were deployed mostly in data centers, but today there are options in many sizes.

Both unmanaged and managed Ethernet switches are reliable devices, but even so standard consumer- or commercial-grade switches are not ideal for harsh or industrial environments, and many not be convenient to install in enclosures. Industrial-grade devices are preferred because they offer more flexible mounting and connection options, along with extended operating temperature ranges and electrical noise resistance, making them suitable for typical installation locations.

Essentials using unmanaged switch

As the need for high-performance and robust Ethernet connectivity is accelerating in many applications, users are taking another look at their options. A recent development is cost-effective unmanaged switches incorporating the following most essential managed features, with no configuration required.

Quality of Service (QoS)

QoS is a method used by switches to prioritize specified network traffic, so the most critical packets are handled first. For industrial applications, there are greatly increasing numbers of Ethernet devices congesting plant networks, creating concerns about communication latency and data loss.

EtherNet/IP is a common industrial automation protocol used for handling crucial communications between devices like PCs, PLCs, HMIs, input/output modules, variable speed drives, intelligent instruments, and much more. Therefore, an unmanaged switch which provides built-in QoS for EtherNet/IP traffic is a great advantage because it automatically guarantees priority for those critical data packets over other general traffic. Users need not configure QoS, but they should be able to easily turn it on/off with a single external DIP switch.

IGMP Snooping

Ethernet traffic may consist of some messages broadcast to all devices, others multicast to select devices, and still other unicast to one specific device. IGMP snooping is a method used by switches to monitor conversations between hosts and routers, and to create and maintain a map or filter of which links need which transmissions.

By delivering messages only where they are needed, IGMP snooping significantly reduces networking traffic and required resources. IGMP snooping is usually desirable, but user should be able to disable it by using the QoS DIP switch if necessary.

Broadcast storm protection

For Ethernet networks installed on-board equipment or within a larger facility, careful design and protocol choice can take advantage of network rings for redundancy. However, improper ring connections can result in duplicate messages that will cause the network to stall. For instance, with standard switches, if any user inadvertently connects two switch ports together, then messages will be repeatedly rebroadcast from the ports, increasing in number until they flood and overwhelm the network. Broadcast storm protection detects this issue and discards duplicate messages. As with QoS, no user configuration is required other than enabling this feature with a single external DIP switch.

Robust networking and form factor

There are a few other considerations designers should look for when selecting a switch for their commercial and industrial applications.

For best flexibility, switches should always operate at speeds of at least 10 and 100Mb/s, with auto-negotiation of the speed, full or half duplex mode, and detection of straight-through or crossover cables.

Store-and-forward technology is the best chose for operation because it ensures each communication frame is fully received into memory and CRC-checked for integrity before forwarding it to the destination. This feature introduces a very short switching delay compared with some other strategies, but it secures the highest-quality communication.

Rugged metal housings are beneficial for industrial use to provide physical strength and superior performance with regards to electrical noise, electromagnetic interference (EMI), and electromagnetic compatibility (EMC), while an IP30 rating means the enclosure is designed such that solid objects larger than 2.5mm can’t enter the housing. Furthermore, the RJ45 Ethernet ports should be supplied with IP30-rated covers to protect unused ports. Users need options to mount the switch to a 35mm DIN rail or a back panel within an enclosure.

It is important to look for an operating temperature range suitable for the environment, and only a few switches can work in the extended range of -40 to 75°C. Even if the full temperature range is not needed, devices with better ratings are built more robustly to provide greater reliability and a longer lifespan. Of course, designers also need to ensure that all approval ratings such as UL508, CE, FCC, and Class I Division 2 hazardous location approval are present as needed. A final note is that many critical applications have redundant power available, so the switch should be designed to accept two separate power supply connections for zero failover time if one power supply fails. Pluggable terminal blocks are a plus to make installation and servicing easier.

Improving network performance

Today’s industrial and commercial applications commonly use large numbers of digital controllers, PLCs, and HMIs—along with increasing quantities of intelligent field devices—all of which rely on Ethernet.

Designers now have options to obtain the best networking price/performance ratio, with simple no-configuration installation, by selecting unmanaged switches which incorporate the most important managed switch features.

Linda Htay, Automation Product Marketing Manager, IDEC Corporation