Wire, cable, and connectors are crucial

As the use of wire and connectors increases with added networking functions and interoperability-–and decreases, as networks simplify-–cabling has become forever crucial in industrial networking applications.

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Wire, Cable & ConnectorsBy Jim Montague, Executive Editor

WITH ALL the cool stuff happening in industrial networking, hardware can be easy to overlook. Wireless and Ethernet seem to be taking over the world. Interoperability is advancing everywhere. Fieldbuses are reaching into intrinsically safe areas. Sensors and transmitters are getting their own web servers. Plant floor and enterprise systems are linking up.

Wires and related components just lie there. Not very exciting.

So, who cares about cables, connectors, and cordsets? Everyone. That is, everyone who knows networking hardware still forms the backbone of their control, automation, and manufacturing applications, and quietly will continue to enable every rookie networking method that emerges in the future. Point-to-point 4-20 mA still dwarfs all other industrial networking methods, though twisted-pair fieldbuses and industrial Ethernet have scratched its surface lately. And, truth to tell, there are some pretty historic shifts occurring among the cable and connector sectors themselves.

Tailoring Cordsets
Faced with smaller, aging staffs and high labor costs, many end users are asking cable and connector manufacturers, systems integrators, or assembly houses to build more and more complex cordsets for them. As a result, more assembly work reportedly is being outsourced to lower-cost labor centers worldwide. Frank Koditek, Belden CDT’s industrial market manager, says his company has seen a big increase in user demand for pre-made cables and connector sets, and that more assembly businesses have grown up to serve that need.

In fact, Jack Gayara, Lapp USA’s connector products manager, claims that his firm’s custom cordset and wiring harness division has seen double-digit growth in the past couple of years, though business has leveled off in the past several months. “This is a very cyclic business,” says Gayara. “When business is booming, then OEMs keep their cordset building in house. When the economy is down a little, they outsource that work.”

“People just need to get into the thought process that their Ethernet network is going to be going into an industrial environment.”

Five or 10 years ago, adds Gayara, there was a lot of relay logic in control panels, so the wires going to the machine had higher pin counts. “Then PLCs combined a lot of that wiring, and pin counts went down,” he says. “Next, newer technologies allowed users to control more functions, and pin counts when up again, until they were reduced by users implementing fieldbuses, Ethernet, and wireless technologies. It seems that cable and connectors’ contacts increase; someone finds a way to simplify, and they decrease for awhile; and future technology allows more monitoring and control functions, and pin counts go up again. These two forces really do seem to balance off each other.”

Ed Nabrotzky, industrial communication general manager at Woodhead Industries, says increasing use of tailor-made cordsets is part of a trend it calls “connectorization.” “Hardwiring usually requires a skilled, union electrician to pull wire, screw on connectors, and address many power and compatibility issues, ” says Nabrotzky. “Preassembled cabling and connectors, or ‘softwiring,’ means less skilled labor is needed, enables more modular design practices, and allows worldwide shipping and servicing far from where components were originally sourced.”

In the past, machines often were designed as one unit. “Now, we can break designs into sub-machines and/or sub-assemblies, and mix and match components as needed by the recipe for the product being produced,” adds Nabrotzky. “We can build a machine in Kentucky, and reassemble it in Eastern Europe.”

This increased use of customized, modular technologies doesn’t stop at the cable. Individual connectors also are multiplying the variety of inserts and contacts to meet increasingly varied demands. "People are using more rectangular connectors with different housing or hoods on the ends, but now we even have modular inserts within them, so we can custom configure for specific applications,” says Gayara. “It’s a lot like Legos. Many users seem to enjoy doing their own inserts. We’ve even added Ethernet to these modular inserts, which gives some flexibility, but maintains a reliable, shielded connection.”

Though much cordset assembly is outsourced, some manufacturers are finding they can do it themselves economically. “We do a lot of assembly work here, rather than sending components to two or three other companies before they reach the end user,” says Kirk Larson, Turck’s project engineering manager. “We’re also seeing work come back from Asia because of quality and lead time. We’re finding we can be competitive in this area.”

Ethernet and M12
Though its presence is still small compared to legacy industrial networks, Ethernet is gaining nodes quickly, and this is fueling demand for Ethernet-based cable, connectors and components that can survive and serve long-term in harsh industrial settings with high temperatures, corrosive fluids, electrical noise, extreme heat or cold, high vibrations, or a combination of these factors.

“Presently, Ethernet only makes up 3% of our cable and connector businesses, but that’s up from zero just a couple of years ago,” says Nabrotzky. “For example, we have the global contract for General Motors’ networking, and they’ve specified having Ethernet in all applications by 2007.”

Despite this push, Nabrotzky adds, automotive production suppliers such as robotics and transfer line manufacturers are still having some problems getting all their devices up and working on Ethernet. “The big vendors say they have a working network safety standard in place, but the drives and robotics guys still are asking how to build these standards into their devices,” says Nabrotzky. “When they try to do it, they find that everything isn’t defined, there are a lot of gray areas, and they have to guess when they try to format a data packet or interpret a signal. There are still a lot of incompatibilities.”

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.

“It’s amazing how much wire and cable it takes to go wireless.”

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.

“Safety automation that gets rid of hardwired stops, but the cable market accelerates anyway because now you need cables devoted to this new technology.”

“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.”

Coming Attractions
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.

Cable and Connector Glossary

The following terms are some the basic instruction included in Belden CDT’s Cable 101: The Basics of Wire & Cable.

  • Attenuation: A measure of a cable’s loss of electrical energy; expressed in dB/unit length
  • Breaking strength: The pulling force, in pounds, that will cause a conductor to fracture.
  • Capacitance: A measure of insulation’s ability to store electrical energy; expressed in picofarads per foot.
  • Dielectric constant: Electrical property that determines capacitance, propagation velocity, impedance, and insulation performance.
  • Dielectric strength: Material’s ability to withstand voltage breakdown; expressed in volts (V) or kilovolts (KV).
  • Flexibility: Ease with which a conductor can be bent.
  • Flex life: Ability of the conductor to bend repeatedly without breaking.
  • Insulation: Substances that electrically and physically separate conductors in a cable.
  • Length of lay: The number of twists in a conductor.
  • Propagation velocity: Transmission speed of an electrical signal through a length of cable; compared to light speed in a vacuum.
  • Skin effect: As its frequency increases, the flow of electrons move to the surface or skin of the conductor.
  • Working voltage: Maximum voltage allowable by UL to be applied to cable; expressed as AC Volts (V) or kilovolts (KV).
  • Shielding: Contains electrical energy so signal on cable doesn’t radiate and interfere with other nearby signals.
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