For a new standard or safety technology to be effective, it must have broad support from vendors to enable interoperability and a stable supply chain for end users. "My view is that Ethernet will be very well accepted as a future technology because vendors are building now, though there aren't enough products yet to allow it to be more widely implemented," concludes Nabrotzky.
Similarly, as safety functions migrate from redundant hardwiring to join the rest of the operating network, some difficulties persist. "The design is to have safe PLCs and verifications, but all the Ethernet safety standards aren't fully developed yet," adds Zabrotzky. "However, there's already harmonizing going on between Europe and the U.S. and between the IEC 61508 and EN 954 standards. They're already referencing each other, and they have common provisions now. For example, the Profibus Trade Organization is putting harmonized standards into Profisafe, and ODVA is releasing its CIP Safety standard.
One trend expected to hasten Ethernet's adoption is that its users have generally gathered around two connector types. RJ45 is already the most-used Ethernet connector worldwide, mostly in the usual office settings, but now these connectors are being made more rugged for industrial settings, and even acquiring over-molding for especially harsh applications.
Users also are adopting traditional, round M12 and M8 four and eight-pole connectors for installing Ethernet on the plant floor. This has triggered an increase in demand for two-pair Ethernet cable, which M12 connectors require, rather than the four-pair Ethernet cables that don't match these connectors.
Turck's Larson says users want more pins and sockets in smaller packages. "M12 used to have just four pins, but now people increasingly want the 12-pin maximum that these connectors can handle," he states. "It's a challenge, but it also opens new markets for us. For example, users are adding IP67 ruggedized RJ45 cables to on-board systems on off-road construction vehicles."
Ethernet Education Essential
Koditek reports that Ethernet can only keep growing on the plant floor if users are educated about industrially hardened cabling and switches that will help them be successful in the long term.
"With all the oil, solvents, and fumes in many applications, degradation can take place, and failures can occur," says Koditek. "Process engineers certainly know their own environments, but they may not know the industrial components they'll need to get Ethernet into these areas. Similarly, when the IT department is asked to extend Ethernet into a factory, it often doesn't know that a commercial Ethernet product isn't good enough. The walls and cabinets where Ethernet historically exists are much more benign, with a much narrower temperature range, and so the jackets on these cables work at the beginning. However, they can deteriorate quickly because they can't withstand the abrasion, oil exposure, sunlight, cold, crushing forces, and other factors on the plant floor. That's when intermittent problems start, and downtime costs begin to come in."
In fact, some of this message might be getting through because, after experiencing slow growth in Ethernet for several years, Koditek reports that Belden has seen strong double-digit growth in Ethernet cabling for the past two or three years.
Wireless Needs Wires
After years of worrying that wireless technologies were going to eliminate hardware, suppliers and users realized sensors and transmitters often need new wires to send wireless signals, and that receivers and PLCs also need cabling to relay that data. Grant Bistram, also of Turck, sums up the industry's favorite punch-line about the new technology, saying, "It's amazing how much wire and cable you need to go wireless."
Woodhead's Nabrotzky adds, "We're not seeing wireless in the discrete automation platform at all. No car plant I know of uses it. Some retailers use wireless technology such as RFID for sorting, handling and logisitics, but they still cable all their automation. Wireless is being used in the process industries in remote telemetry units (RTUs) that collect and control I/O data slowly, over long distances, and in wide open spaces."
In the end, Koditek says wireless and wire likely will co-exist peacefully on the plant floor with each doing the jobs it does best. "Wired infrastructures are more secure and stable, but wireless is more flexible, and more easily can advance performance to where it's needed, such as hooking up and accessing remote sensors," he adds.
Do You RoHS?
Perhaps the most substantive physical change in wire and cabling in recent years was driven by the Europe-based RoHS regulations requiring lead-free, non-heavy-metal composition in a variety of hardware and other components. Major manufacturers already have spent several years gearing up to comply with the new rules, which officially take effect in July 2006, and already are getting rid of non-RoHS-compliant inventories. This process reportedly hasn't been easy because many cable manufacturers have had to find substitutes for the heavy-metal additives that often helped make their cables more flexible and durable.
"We spent a couple of years working on this technical challenge, but we haven't had to change specifications, we haven't lost any capabilities, and we've been able to mitigate most of the cost impacts, so there's minimal if any effect on our customers," says Koditek. "Now that most of the compound changes are pretty well set, we can continue looking at getting higher performance from these cables, whether it's increased system speed, more data capacity, or better quality signals."
Nabrotsky adds another reason for softwire's growth is that the National Fire Protection Association (NFPA) revised its rules in 2002 to allow higher-voltage power, typically 30 A and 600 V, to be supplied via softwiring with factory-applied, molded connectors. Again, this design simplification reduces labor and potential errors, but it also fits with how cables and connectors have evolved in recent decades.
"Simple tool cords began to be used in the 1970s, and these branched into networking in the 1990s and softwired power in 2002," says Nabrotzky. "Next, we're seeing safety automation that gets rid of hardwired stops. This means you no longer need cables for that task, but the cable market accelerates anyway because you do need new cables devoted to the new safety automation."
Nabrotzky adds that future developments also will include more data and power combined in the same system, especially when a Power over Ethernet (PoE) standard is completed. He also expects DeviceNet and AS-i to tie power and data onto the same cable.
Connector Methods for Networks
Most industrial networks use one or more of the following three connector technologies:
- Mini: These connectors are based on a 7/8-in wide barrel with a 16 pitch. They usually consist of two through seven-pin connectors.
- Euro or Micro (DC): These are based on M12 threads, and have a coupling unit that's about 14 mm wide. They include two through six-pin connectors.
- 9DB: These include D-shell, subminiature connectors typically with nine pins.