Getting your signals straight

If control software can be compared to human nerve impulses, then wire and cables are the nerve fibers they travel over. Wire and cable for networking and communication is responsible for taking data from field devices and transporting it to a processing device, such as a PC or PLC. The PC or PLC (brain) can then decide how it will act.

11/01/1999


Trends in wire and cable

 

  • Standard twisted pair

  • Shielded

  • Noise immunity

  • Environmentalprotection

If control software can be compared to human nerve impulses, then wire and cables are the nerve fibers they travel over. Wire and cable for networking and communication is responsible for taking data from field devices and transporting it to a processing device, such as a PC or PLC. The PC or PLC (brain) can then decide how it will act.

Control Engineering 's 1999 Wire & Cable Study looks at the 'nerves' involved in networks and communication (N&C). The study sought to qualify respondents' involvement in recommending, specifying, and/or purchasing wire and cable for industrial N&C; examine types of wire and cable used; investigate information necessary to pick the correct type or gauge of N&C wire and cable; and determine the importance of selected N&C wire and cable characteristics in purchasing decisions.

CE polled 1,500 readers and received a 16% response rate. Of the 239 respondents, 67% specify, recommend, and/or buy wire and cable for networks and communication; 20% do it for OEM (resale) requirements; and 6% do it for both.


Still doing the twist

Standard twisted-pair wire is still an industry favorite, with 91% of respondents saying they specify, recommend, or buy it, and 74% saying they've purchased it in the last 12 months. Among wire and cable purchasing preferences, standard twisted pair is followed by accessories, flexible variable frequency drive, and fiber optic (see graph).

Respondents most used cable developed for specific applications. For example, as one might expect, shielded wire and cable was used most in applications where EMI and RFI resistance are important (61%), or in noisy applications (50%) where recurring noise problems threaten signal integrity.

Chemical and oil resistant wire and cable scored well with applications in which machine oils may damage wire (43%). It's also used often in hazardous and outdoor environments, and in locations subject to frequent washdowns.

Shielded wire and standard twisted pair are considered among the most versatile wire and cable used today. Both received the highest average use in all applications in the survey, with 20% and 11% respectively.

Use of flexible cable is expected to gain market share over the next five years, respondents say. The percentage of flexible cable currently in use is about 23%. By 2004, respondents say that will increase to about 28%, (see graph next page).

Stationary cable manufacturers need not worry yet, says Eric Bulinger, marketing specialist for industrial markets at Belden Wire & Cable (Richmond, Ind.). He says less stationary cable may be sold in the next five years, but because that cable will be more advanced and hence, more expensive, the total dollar amount may stay the same.

Mr. Bulinger says the next advance necessary is a truly flexible data cable for such networks as DeviceNet and Profibus. 'It's where the biggest technological leap needs to be made.'

Respondents are divided almost evenly when asked if they use cable carriers. Forty-nine percent say they do, 40% say they don't, with 11% not answering.

Why would respondents not use cable carriers? 'It depends upon the application,' Mr. Bulinger says. 'The fewer the wires, the less likely carriers will be needed.' He adds fieldbus cable and wiring topologies render carriers unnecessary in some cases. With fieldbus, users move from point-to-point wiring to a topology where one main line is connected to several drops. Fieldbus topologies eliminate a lot of wire, so carriers are not needed.


Choosing your product

'Wire and cable has historically been an afterthought,' says Brian O'Connell, general manager for Alpha Wire (Elizabeth, N.J.). 'However, it's usually the first component to fail in an automated system.' Mr. O'Connell says users need to spend more time when purchasing wire and cable, and that safety should be of primary importance when users choose. Some factors he believes users need to consider are current carrying capacity and voltage. Current carrying capacity determines wire gage, and voltage determines how much insulation a wire or cable needs. 'The NEC [National Electrical Code] will point [users] in the right direction.'

Respondents agree with Mr. O'Connell. Other information they said needs to be considered before buying includes:

  • Environmental issues-Users must choose wisely if the wire and cable they buy will be exposed to chemicals, oils, ultraviolet rays, temperature resistance, or frequent washdowns. Other factors are special locations, distance, and routing.

  • Equipment specifications-Manufacturers will usually provide a spec list to make sure connected equipment works properly.

  • Load and signal type-Respondents say they must know load requirements and resistance ratings, along with signal characteristics, and strength.

To aid customers with their choices, Mr. O'Connell says Alpha Wire sends an application engineer to the customer's site with an application guide. It's a checklist the customer and Alpha's engineer use to examine many of the factors listed above to make the right purchase.

Mr. O'Connell says Alpha also benefits from this collaboration. The information it gets from these meetings can be used by Alpha's design teams.

Belden Wire & Cable has a similar program. Mr. Bulinger says his company has developed an engineering center that trains engineering employees to make sound decisions when suggesting wire and cable. Often, Belden engineers too will go out in the field to examine a customer's application and help them make the right purchasing choices.

Quality, delivery, and price are respondents' most important requirements when purchasing wire and cable.

Belden's Mr. Bulinger says customers also look for packaged solutions. They not only need customized cable, but the connectors to go along with it. He sees more partnerships developing in the near future between cable companies and connector companies to accommodate these customer requests.

Purchasing

For the next year, the market for N&C wire and cable looks to be steady at least, if not better. Sixty-one percent of respondents expect their companies' purchases of N&C wire and cable to remain about the same over the next 12 months, and 23% expect purchases to increase. Only 5% expect N&C wire and cable purchases to decrease in the next year, while 8% are uncertain.

Wire and Cable Products

For more information on wire and cable products, go to www.controleng.com/freeinfo .

Cordset with LED

Minneapolis, Minn.- RKE 4T has been added to Turck's 'eurofast' cordset line. LEDs encircle the cordset's connector, visibly indicating power and signal; green LEDs for power and yellow for output. The cords are reportedly ideal for connecting sensors without LEDs. The cordset has the M12 connector, an industry standard for dc devices, gold-plated contacts for electrical conductivity, and brass coupling nuts machined from solid stock for secure connections. The coupling nuts' ratchet design prevents loosening during high-vibration applications. The polyurethane connector body resists moisture, oil, solvents, and abrasion. The cordset meets NEMA 1, 3, 4, 6P, and IEC IP68.

Turck

Cable for harsh environments

Fairfield, N.J.- Olflex Wire and Cable offers a variety of flexible fieldbus cables for use in high-speed manufacturing environments. Designed with special materials and manufacturing techniques to provide precise bidirectional data transmission in multitask environments, these cables can be used for connecting online bus system components in DeviceNet, AS-i, Genius, Interbus, and Profibus applications. Available in flexible, flexing, and stationary versions, Olflex fieldbus cables offer protection from electrical interference.

Olflex Wire & Cable

Wire wrap for easy identification

Burgaw, N.C.- Spiroband is a flexible wire wrapping that provides easy identification of wire bundles while protecting them and keeping them in place. They're available in eight colors as well as a variety of materials. Spiroband requires no tools for installation and can be close-wound or spaced according to the rigidity of the particular bundle. Spiroband is moisture-proof, nontoxic, and highly resistant to most acids, alkalines, and oils at ordinary temperatures. Materials available are low-density, natural, ultraviolet and weather resistant, and flame-retardant and self-extinguishing polyethylenes. Spiroband is also available in nylon and Teflon. Pitch ranges from 9/64 to 1 5/8 in. with bundle range diameters from 1/6 to 8 in.

Wieland

Multimode backbone for gigabit Ethernet

Nashville, Tenn.- AdvanceLite 2000 fiber-optic cable incorporates Corning InfiniCor CL 2000 fiber. This fiber guarantees performance for gigabit Ethernet transmission while maintaining backward compatibility with existing networks. It also guarantees a transmission distance of 2 km for 1000Base-LX compliant networks with no mode conditioning patch cord. The company says, 'This product is the final piece of the puzzle to provide a complete migration path from LED-based networks to laser-based networks.

Mohawk/CDT

New models added to cable line

Elizabeth, N.J.- Alpha Wire has added two new models to its Xtra-Guard series of cables. New to the series are Multipurpose and Continuous-use flexible cables. The company says Xtra-Guard cables are 'hazard matched' to virtually any environment. Models are available to handle extreme heat or cold, oily and caustic environments, and even underground applications. Users can save time and money on installation because Xtra-Guard cables do not need conduit systems. Xtra-Guard is also available in small put-ups of 100, 500, and 1,000 ft.

Alpha Wire Co.

Multimedia support

Richmond, Ind.- MediaTwist is billed as being the 'first open architecture' multimedia cable. It's an unshielded cable designed to support audio, video, data, broadband, and telephone applications, even simultaneously, using each of the four pairs to carry an individual signal. It passes the Underwriters Laboratories Class A certification for digital devices. MediaTwist is available with 24 AWG solid bare copper conductors for both plenum and nonplenum installations. The plenum versions are FEP and polyolefin insulated and have a flame-retardant jacket with ripcord. Nonplenum versions have polyolefin insulation and feature a PVC jacket with ripcord.

Belden Wire & Cable

Test tools for cable installers

San Diego, Calif.- Cable Verifier (CV) Series is a new line of cable and connection troubleshooting tools. They range from a LAN and telecommunications tester to a LAN multicable checker and traffic detector. The testers are reportedly small enough to fit in shirt pockets, tool kits, and tool belts. Testing can be as simple as plugging the connectors into the tester and viewing status on the front-mounted LED array. For LAN cable applications, there are nine new CV models. CV 50 Series test some combination of 10Base-T, T568, Thinnet, and Token Ring.

Wavetek

Channel cabling

Skokie, Ill.- Anixter Levels Channels (ALC) is the company's specification for an entire structured cabling system 'from the PC to the hub.' The system is reported to help customers select and design a reliable data cabling infrastructure that allows them to run current and future applications without trouble. ALC offers three performance levels of channel solutions: ALC 5 (Ethernet), ALC 6 (Fast Ethernet), and ALC 7 (gigabit Ethernet). Specifications for ALC conform to all existing and proposed standards at minimum. To ensure optimal system effectiveness, each component must meet the Anixter Level 5, 6, or 7 requirement individually, as well as with other components as a combined ALC 5, 6, or 7 system. The company custom matches every part of every ALC solution it recommends.

Anixter

Cable and connection system for DeviceNet

Midlothian, Va.- IP67 rated Multimate Connection system for DeviceNet consists of new Flat DeviceNet cable, modular bases for flat or round cable, and interchangeable I/O modules. Multimate Connection and Cabling System is said to offer a virtually 'enclosureless' solution with cut-to-install cabling options and industrial connection and I/O options. The keyed flat cable technology allows the use of IDC (insulation displacement connectors) to place the field device I/O nearly anywhere on the cable without the hassle of stripping wires in the field, wiring errors, or complicated cable length estimates. Advanced diagnostics and modular design layout of Multimate I/O modules simplify cabling circuitry and reduce wiring.

Lumberg





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