Ethernet is widely used among consumer and commercial systems throughout the world, and it is well understood by all levels of end-users. Due to economies of scale, coupled with availability of industrial-grade devices, Ethernet has also become suitable, and often dominant, for many types of more rigorous applications. Unfortunately, industrial-grade Ethernet devices are often associated with high costs and complex network management and configuration requirements.
Because industrial equipment and test systems call for equally high-performance networking, designers are looking for ways to apply the technology, but in a cost-effective and practical manner. Industrialized unmanaged Ethernet switches are now available to meet this need by providing the key features of managed switches in an economical and easy-to-use format.
Throughout a wide variety of industries, including manufacturing, processing, municipal, and test system applications, devices of all types are becoming more intelligent, and they naturally include communication capabilities. This networking is often based on Ethernet, using one or more industrial or IT-centric protocols (Figure 1). Common supervisory and control devices include PLCs, HMIs, and PCs, using operations technology (OT) protocols like EtherNet/IP, Modbus TCP, OPC UA, and others. Field devices may be input/output components, smart sensors, motion controllers, advanced devices like process analyzers and RFID readers, and others. Transporting field data to other enterprise IT resources falls under the description of industrial internet of things (IIoT) projects and relies on protocols like MQTT.
Standard wired Ethernet can only support cable lengths of 100 m, and each target device requires a unique physical connection. Therefore, multi-port switches are typically installed relatively close to the field devices. Most basic Ethernet switches are unmanaged plug-and-play devices, and they auto-configure to match each connected device, and they build a MAC address table to forward traffic with some level of efficiency. They are economical, and suitable for simple applications, economically providing adequate performance, but without much flexibility or cybersecurity.
Robust networking performance for 24/7 applications typically requires managed switches for increased speed, efficient traffic handling, and improved cybersecurity. However, as their name implies, these switches must be administrated by trained IT personnel. Managed switches originally were used mostly in IT data centers, but they are increasingly needed at the OT edge.
Users seeking industrial-grade networking options in an easily configured format are finding switches requiring only minimal management often meet their needs (Figure 2). Some basic characteristics of these devices should include:
- Robust performance: 10 and 100 Mb/s speeds, auto-negotiation, full/half duplex, and CRC-checked store-and-forward technology to ensure each communication frame is fully and properly handled.
- Flexible mounting and connection options: DIN and panel-mount options, with IP30-rated covers to protect unused RJ45 ports, pluggable terminal blocks, and able to accept redundant power supply inputs.
- Designed to survive harsh environments: Rugged metal housings, operational over an extended temperature range of -40 to 75 degrees C, rated IP30, with UL508, CE, FCC and Class I Division 2 hazardous location approvals as needed, and a high level of resistance to electrical noise and electromagnetic interference.
- Simple configuration of the most essential managed features.
These traits are not available in typical unmanaged industrial Ethernet switches. In particular, the following managed switch traits are most important for industrial-grade applications:
- Quality of Service (QoS): Prioritizes the most critical traffic. Usually only available on managed switches, QoS for industrial applications can ensure that EtherNet/IP packets — used extensively for crucial automation tasks — are handled first.
- Internet Group Management Protocol (IGMP) Snooping: Reduces network traffic and resource loading by actively monitoring and optimizing transmissions.
- Broadcast Storm Protection: Discards duplicate packets in the event a user creates an improper ring connection.
Smart unmanaged Ethernet switches should use simple DIP switches so users can easily adjust their configuration, without requiring online configuration.
Availability of industrial-grade, smart unmanaged Ethernet switches with a favorable price/performance ratio means there is simply no reason to use anything less for any type of application involving intelligent controllers, sensors, and other devices.
This article was written by Linda Htay, Automation Product Marketing Manager, IDEC Corporation. For more information visit here .