Ethernet hardware switches, connectors, and parade of other products

Ethernet is picking up steam, speed and force. Enabled, durable components are multiplying. Reliability and security are improving. Costs are decreasing. True interoperability is gaining ground against proprietary pressures. Standards are being developed. And, yes it's true, some information technology (IT) staffers and plant-floor engineers are actually talking and cooperating on networking pr...

By Jim Montague, CONTROL ENGINEERING August 1, 2002
  • Networks and communications

  • Ethernet

  • Device-level networks

  • Fieldbus


Ethernet is picking up steam, speed and force. Enabled, durable components are multiplying. Reliability and security are improving. Costs are decreasing. True interoperability is gaining ground against proprietary pressures. Standards are being developed. And, yes it’s true, some information technology (IT) staffers and plant-floor engineers are actually talking and cooperating on networking projects, including Ethernet. So, if you, your colleagues, or your management would like to jump on the Ethernet bandwagon and join the parade, it’s getting easier to do.

In fact, Control Engineering/Reed Research’s Industrial Networking Product Focus Study , January 2002, found that 87% of 439 control and automation professionals presently use Ethernet and 89% plan to buy some Ethernet products in the next 12 months. (See “Product Focus, Trends in Industrial Networking,” CE, Jan. ’02, p. 40). Likewise, a recent report by Venture Development Corp. (Natick, Mass.) found that industrial and remote I/O devices with Ethernet interfaces will increase from 11% of the total device market in 2000 to 26% of the total in 2005.

Needs drive implementation

To bring Ethernet to the plant floor, users must complete several crucial tasks, depending on the needs of specific applications and their environments. As always, network developers must first ruthlessly evaluate their applications’ present and future requirements and business goals to decide which network capabilities and Ethernet-related hardware are most appropriate.

Implementing Ethernet includes relatively sophisticated tasks, such as determining proper network topologies and distances, redundancy levels, and switches to ensure safe, efficient network performance. “When you’re networking PLCs, smart devices and I/O points, there is more potential incompatibility. Users must check what protocols their Ethernet devices and networks support. You can’t just buy everything that says ‘TCP/IP’ on it,” says Perry Marshall, author of Industrial Ethernet: A Pocket Guide . As a result, many users now require suppliers to demonstrate interoperability before they buy Ethernet components and other networking hardware.

No less crucial, however, is the informed selection of cables, connectors, converters, hubs and other basic hardware, as well as securing sufficient protection for each. “If you’ve got an isolated network with three remote I/O racks, one controller and one HMI workstation, then you can probably use a less expensive Ethernet switch. However, if you have a more complex network or you need data updated every 10 msec, then you’ll need a higher-performance switch,” says Anatoly Moldovansky, senior project engineer for NetLinx at Rockwell Automation (Mayfield Heights, O.).

Rockwell generally recommends implementing Ethernet components that operate at 100 Mbps; include switches that prioritize data and filter unauthorized traffic; and have full-duplex capabilities that allow data to be transmitted and received simultaneously without colliding, which ensures the determinism crucial to many applications.

Cables, connectors, switches

Because most of its hardware originated in office settings, Ethernet typically uses RJ-45 connectors, Velcro-secured mountings and other light-duty components that are frequently unsuitable for manufacturing environments. Lately, many suppliers have produced more robust cables, connectors and other DIN rail- and machine-mountable components to bring Ethernet to the plant floor, where dirt, dust, heat, cold, moisture, vibration, chemicals, corrosives, electrical noise and other hazards can hamper network performance.

“Just checking the temperature where you’re going to deploy Ethernet can be very important, which is why we offer Ethernet components for outdoors and unregulated temperature environments from -40 to +70 °C,” says Frank Madren, president, GarrettCom Inc. (Fremont. Calif.). GarrettCom’s Magnum P62F and P62F-5V Ethernet switches include six 10/100-Mbps switched RJ-45 ports and two 100-Mbps fiber-optic ports than can be linked to local devices and strung over long distance networks.

To support switches and other Ethernet-based components, cabling must also be evaluated carefully. For instance, while Cat 5 cable is fine for office-based settings, Siemens Energy & Automation (Norcross, Ga.) recommends Cat 5e twisted-pair cable for connecting its 100-Mbps, full-duplex electrical and fiber-optic Ethernet modules, says Bill King, Siemens E&A’s networking consultant.

To better handle harsh settings, Industrial Communication Technologies (ICT, Newburyport, Mass.) recommends Lumberg Inc.’s (Midlothian, Va.) etherMate M12 connectors, which include RJ 45-M12 bulkhead receptacles; ICAT5e braided and shielded cables; and PUR over-molded M12 connector cordsets.

Topology, fiber helps security

Though it’s well known that Ethernet switches and routers can prioritize and segregate data traffic, which isolates plant floor sub-networks for secure operation, developers also rely on topology and network design to aid their security efforts.

Ring and star topologies are the most popular designs for making Ethernet secure. These configurations often use intelligent switches that monitor the network, and can immediately reroute traffic if and when a portion of the network goes down. For example, Phoenix Contact’s (Harrisburg, Pa.) Factory Line switch, FX/FX, has five 10/100-Mbps, twisted-pair Ethernet connections and two 100 Base-FX multi-mode glass fiber connections, which can be used to create a redundant Ethernet ring with fast reconfiguration time. In the event of a segment interruption or other error, the switches ensure restoration of a functioning network in less than 500 msec for 50 switches.

“In fact, switches with built-in web pages can be managed remotely, while some can be instructed to monitor their own connections with devices, and trigger alarms if those connections are lost,” adds Sven Burkhard, sales and marketing manager operations manager, Hirschmann Electronics Inc. Pine Brook, N.J.)

Likewise, AutomationDirect (Cumming, Ga.) reports that its EZTouch panels can be programmed directly over its PLC Ethernet network using off-the-shelf Ethernet hubs.

Siemens’ Mr. King explains that, while a ring requires an extra piece of cable, it usually can switch over within 300 msec when a break occurs. Similarly, ring topologies have to experience statistically unlikely two points of failure before beginning to lose data, while a break in a traditional line or bus configuration immediately loses communication with all devices further down the line.

Mr. King adds that copper cabling is best for runs up to 100 m, but users can avoid installing chains of repeater devices by applying fiber-optic cable for longer runs. Multi-mode fiber can be used for up to 3 km, and single-mode fiber can travel up to 15 km, he says.

Communications and analysis

Logically, as Ethernet networks grow more complex, more sophisticated hardware is needed to help them function properly. Routers manage overall communications traffic between networks according to pre-defined parameters, while device servers further simplify those communications.

“When several computers talking several protocols want to talk to one device simultaneously, Digi One IA device server is the agent they can all talk through at the same time,” says Joel Young, vp of device server products for Digi (Minnetonka, Minn.). “All messages get to the right place because Digi One IA’s Multi-Master capability talks to the destination devices.”

To observe activity on an Ethernet network, and perhaps make it seem more real to skeptical engineers, there are a variety of diagnostic devices for Ethernet-based networks. Woodhead Connectivity (Northbrook, Ill.) provides NetAlert software, which flags errors and allows observation of traffic and bandwidth data, according to Bob Neagle, manager of Woodhead’s Industrial Ethernet Group.

Similarly, the Fieldbus Foundation (Austin, Tex.) recently released its AT-440 High-Speed Ethernet (HSE) Analyzer Toolkit, which includes a packet analyzer, example field device and design example, and reduces product development time by helping engineers quickly find and diagnose errors in packets from HSE devices.

Hardware aids cooperation

Not only does effective Ethernet hardware aid implementation and reduce costs, it also appears to smooth some personnel issues. “In the past, control engineers dreaded working with the IT side on networking projects, and it was very hard to bring them together,” says James Davis, a systems engineer at Opto 22 (Temecula, Calif.). “However, newer, Ethernet-enabled components, such as our Snap Ultimate I/O, make it much easier for them to cooperate.

“For example, when an engineer shows IT staff the specs needed to bring I/O points to a real-world device, their relationship is now much better because they don’t have to buy a lot of middleware. All structured query language databases recognize Snap Ultimate I/O without having to add additional equipment.”

Also, because many IT departments are in charge of assigning public and private IP addresses for their networks, Mr. Marshall [author of the Guide mentioned earlier] adds that they can help increase network security by assigning private addresses to devices on the plant floor.

Future flexibility

Besides generating wire and labor savings now, Ethernet’s potential openness and interoperability gives users added flexibility to expand and reconfigure their networks in the future. Ethernet’s flexibility allows it to form connections beyond its initial network, and reach out to the Internet, wireless, and other settings. For example, iServer from Newport Electronics (Santa Ana, Calif.) is a DIN-rail-mountable Ethernet-serial bridge and Web server that can work as a hub connecting up to 32 instruments to Ethernet and the Internet. The iServer can also connect almost any RS-232 or RS-485 serial device to Ethernet.

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For an expanded version of this story, an Ethernet standards update, and more Ethernet and related hardware resources, visit

Also, online, “10 Industrial Ethernet installation issues,” based on information from a guide by Contemporary Controls