Today's Ethernet promises big benefits across all levels of industrial control. But one major question remains for automation and control engineers: Can standard RJ45 connectors and CAT5 cables, designed for the front office, survive out back on the factory floor?
At least three companies don't think so. Not when it comes to taking Ethernet components out of the protective confines of the enclosure (IP20 or less), and putting them in the harsh (IP67 or greater), dirt-filled reality of shock, vibration, moisture, and extreme temperature.
That's why in a joint press briefing at National Manufacturing Week in Chicago in March, Lumberg, Commscope, and Interlink BT announced a ruggedized Industrial Ethernet field-interface solution that's really ready for the plant floor.
|No big size difference: With only a small size difference between an RJ45 and an M12, it's easy for engineers to design the M12 into existing RJ45 form factors.|
The system supports legacy RJ45 connectors within protected environments. However, etherMATE? RJ45-M12 bulkhead receptacles from Lumberg (Midlothian, VA) seamlessly convert the RJ45 connectors inside the enclosure to the tried and proven threaded M12 form factor outside of the cabinet. Connector cordsets and patch cords tie everything together with shielded and braided ICAT5e cable. The new industrial-grade cable was specifically developed by Commscope (Claremont, NC) to handle different combinations of noise and flex that are found in industrial environments. To complete the new industrial Ethernet solution, Interlink BT (Plymouth, MN) talked about its industrially hardened Ethernet switches, routers, and hubs, and how they will provide completely enclosure-less Ethernet connectivity to reduce cabinet real-estate on the machine, decrease maintenance, and simplify installation.
Given Ethernet's momentum today, about the only thing that could stop it dead in its tracks is the sour taste of factory-floor failures in the mouths of automation and control engineers. Radiographic inspections indicate that the RJ45 connector just isn't up to the task of implementing Ethernet on physical field devices, according to Sundar Balu, product manager industrial automation products at Lumberg. Given the RJ45's spotty reliability in the office environment, Balu says, he doubts a snap-fit connector with such thin contacts can survive and transfer signals reliably over time in the harsh world of shock, vibration, and temperature extremes.
Balu explains that sampling 30-40 different RJ45 connectors in terms of pullout and insertion forces, strain, locking, and sealing, revealed that most of the commercial-grade connectors weren't in sync with each other in terms of performance. "That's not something we are willing to take a chance on," he says. Since M12 connector technology is tried and proven, it makes sense to consider it for Ethernet.
An industrial standard. Since M12 form factor was first developed by Lumberg 20 years ago, it has found application in many industrial sensor, switch, actuator, and pc board applications. The IEC commission regulates the M12 standard today for a growing number of fieldbus applications, including ASI, Foundation Fieldbus, DeviceNet, Profibus, and SDS. It's a proven, off-the-shelf, harsh-duty standard that's potted, sealed and provides shield-to-ground termination capability for both single-point and multiple-point grounding.
|Commscope's noise and flex selection matrix helps engineers pick the proper cable. All four grades are constructed of materials that reduce the effects of UV and fluids such as oil and chemicals.|
The M12's threaded housing provides a secure fit, and engineers can vary contact size and material for specific applications. "It offers excellent protection against moisture buildup, dust, corrosion, EMI/RFI, vibrations, and shock," says Balu. "And it doesn't create any new implications for the existing environment where people are already using RJ45 inside of a cabinet."
With 100Base-Tx and even Gigabit Ethernet implementations on the horizon, noise immunity is more critical than ever, explains Commscope Engineering Manager Steve McAnulty. "Greater data rates require greater shielding spectrum to head off the detrimental effects of noise." That's why Commscope has leveraged its expertise in LAN cabling, to bring four flavors of ICAT5e (Industrial category) cable to the industrial market.
InterlinkBT displayed one of its newest Ethernet Repeaters-an eight-port, 10BaseT Ethernet hub designed for industrial applications, at the press briefing. The hub's rugged construction withstands harsh environments, enabling Ethernet implementation where it was previously impossible, according to Bob Svacina, marketing director at InterlinkBT. "It offers the features and performance of traditional hubs used in the office environment, but its durable aluminum housing is rated NEMA 6 and IP67 to eliminate the need for additional enclosures."
The Ethernet Repeater manages communication and delivers regulated power for field devices, and monitors hub traffic continuously. In fact, Svacina notes, because the hub can operate in full duplex mode, the old data collision concerns are put to bed."
Compared to using point-to-point control, Ethernet allows engineers to reduce total automation costs. And with these new industrialized Ethernet products to choose from, most of the reliability issues should soon be put to rest.
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