A Structured Approach to Cabling

July 17, 2014
As more manufacturers deploy Ethernet with an eye toward the leveraging the possibilities of the Internet of Things and Big Data, it’s easy to overlook the structure that make it all possible—cabling. Here’s how a structured approach to cabling can future proof your industrial network.

Amid all the interest in Cloud Computing, Big Data, the Internet of Things, and wireless connectivity in industrial applications, one thing is certain—cables are not disappearing any time soon. Though industry’s cabling requirements have changed dramatically in the Ethernet age, they remain central to industrial network infrastructure.

To get a better idea of what manufacturers need to focus on to ensure the viability of their network cabling infrastructure, I spoke with Andy Banathy, industrial automation solution architect at Panduit, a provider of electrical and network infrastructure systems and support services.

Panduit supports both structured and traditional point-to-point cabling, but it is structured cabling that is best positioned to support the future direction of automation technology developments. In essence, structured cabling refers to a set of cabling and connectivity products that integrate data, voice, video, and control, as well as system management technologies.

“Structured cabling systems are capable of evolving with the future,” says Banathy. “Industrial data rates eventually will meet and potentially surpass the 10-gigabit per-second level already common on the IT side. Meanwhile, industrial processes and machines are becoming more intelligent, employing advanced instrumentation, sensors and wireless technology. Gaining the full benefits of structured cabling requires an equally systematic approach to conceptualizing, specifying, installing, testing and maintaining plant wide networks.”

Banathy explained that structured cabling systems comprise several subsystems:
• The demarcation point, where the telephone or Internet company ends and connects to the on-premises wiring.
• The equipment or telecommunications room, which houses equipment and consolidation points.
• Vertical or riser cabling, which connects equipment rooms, usually between different floors.
• Horizontal wiring that connects equipment rooms to individual outlets or work areas, usually on the same floor.
• The work area, where user equipment connects through outlets to the horizontal cabling system.
• Entrance Facility — the location where external communications enter the facility. This serves as the demarcation point between the standards and regulation requirements for outside plant vs. inside plant.
• Equipment Room (ER) or Data Center (DC) — the top level of enterprise/building network and may link to higher level corporate network and business system tiers.
• Enterprise Telecommunications Rooms (TR)—Houses the horizontal and backbone cable terminations and distribution switching. Cross-connections of horizontal and backbone terminations using patch cords to extend services to telecommunications outlets may be performed here.
• Enterprise and Factory Riser (Backbone) Cabling — Connects the enterprise ER/DC to enterprise TRs and to the Industrial TR (micro data center).
• Enterprise Horizontal Cabling — Connects the enterprise TRs to zone cabling systems, intermediate distribution frames or wall outlets.
• Micro Data Center (MDC) — A specialized TR that provides a logical separation of equipment and facilities between the enterprise and factory networks.
• Work Area or Cell Horizontal Cabling — Connects the MDC to the factory outlets, zone cabling systems, control panels, consolidation points and zone cabling (routed via trays, conduits and J-Hooks).
• Enterprise and Factory Outlets/Cabling — Work area components from the outlet of the horizontal cabling to the enterprise or factory work area equipment (connected with equipment or ‘jumper’ cords).

Building a Structured Cabling Network
The most effective way of deploying industrial Ethernet networks, according to Banathy, is to “physically distribute cabling runs using a zone cabling architecture for all plant networks.” Zone cabling enables facility systems to be converged with Ethernet cabling pathways. These systems are converged within a common pathway and then terminated within zone enclosures distributed throughout the plant. This accommodates frequent downlink moves-adds-changes typical to the factory floor.

Cabling in these subsystem areas follows a defined form referred to as “the channel,” says Banathy. The channel is composed typically of an equipment cord (a patch cord at the equipment end), the permanent link (fixed, solid conductor cabling) and a work area cord (a patch cord connecting to a work station).

The permanent link is a pivotal feature of a structured cabling system because it allows the uplink to be tested from the machine to the higher-level network, helping ensure the connection and the machine both will perform as needed. “Likewise, in a ring network that connects multiple processes, a structured cabling configuration allows each link to be tested,” Banathy adds. “In addition, having spare permanent links accommodates future growth on the factory floor.”

Herein lies one of the biggest differences between structured cabling and traditional point-to-point cabling: Point-to-point cabling systems seldom, if ever, involve testing. “Instead, when plant personnel need to add another machine or extend the reach of a cable, they may simply use a patch cord and plug it into a switch panel,” says Banathy. “Some experienced control engineers are accustomed to creating their own patch cords by stripping off the jacket on a wire and attaching a connector on each end. These patch cords terminate in a plug, rather than a jack. These practices don’t always provide a future-proof cabling infrastructure.”

One problem with such point-to-point practices is that they are often appropriate only for shorter patch-cord lengths. If a patch cord is extended to 80 or 90 meters, however, it can fail to deliver full performance due to less conductivity and higher insertion loss than the solid conductor cabling used in structured cabling systems.

Structured Cabling Checklist
To implement and maintain an optimal structured cabling infrastructure, Banathy suggests following these steps:

1. Get educated on common best practices for critical fiber and copper connections within network infrastructures. Banathy specifically stresses learning how to:
• Terminate horizontal runs to patch field connectors to form permanent link;
• Validate performance with standards-based tests and equipment;
• Easily replace patch cords if they are damaged or suspect. “You do not need to touch the horizontal cable,” adds Banathy; and
• Improve troubleshooting with well-identified, structured connections that support staff can easily manage.

Banathy also suggests learning the standards and best practices established by organizations such as the Telecommunications Industry Association (TIA), the IEC, and industrial protocol groups such as ODVA and promoted by Industrial IP Advantage.

2. Establish goals and objectives. Assess your needs today, while keeping the future firmly in mind. Where will your operation be in 10 to 15 years? With structured networking, industrial plants become more scalable, especially if they invest in the recommended 30-to-40-percent high performance spare cabling at the time of initial installation.

3. Design the infrastructure and draft specifications. Develop a specification document that establishes your structured cabling standards, and the materials required for your particular operation. Specifications should cover how to implement the plant network for reliability, security and physical considerations. Those include the integrity of the cabling itself, since substandard cabling could come with serious consequences.

Banathy points out here that IT and automation personnel should collaborate on the specification document to drive best practices throughout their facility.

“Specifications often detail how to implement structured cabling to connect the enterprise level to distribution zones, and how to bring cabling into the process and individual machines,” he says. “This document also allows you to specify your standards on required bandwidth performance, so you have consistency for today and be ready for the future. You also can specify where it’s critical to locate testing patch points and what your requirements are for testing.”

4. Installation. Because of the many details included in installation, this is the step with the greatest potential for error. For example, plants that want to support gigabit per second communications may buy the correct Category 6 cabling, but it must be installed correctly to deliver that rate.

“Make sure your installer understands the intricacies of working with structured cabling,” notes Banathy. “They need to be aware of details like bend radius and the twist of the cable, the routing, and protecting the network from noise sources.”

5. Testing. Without testing, you risk startup delays, downtime, callbacks to the manufacturer and a host of other costly huge headaches. In addition, best practices call for documentation on testing results from your installer.

6. Operations and maintenance. The system ultimately becomes the responsibility of the industrial automation user. A common problem is the return of the old point-to-point practices, says Banathy. “Someone on the plant floor may decide to put in a new cord to solve a problem or serve a temporary need. But more problems can arise if they don’t bundle it correctly, or fail to identify the connection. Soon, you could have multiple dangling cords and no idea why.”  He points out that such patchwork problems can be avoided by clearly establishing and strictly enforcing operational and maintenance policies regarding structured cabling networks.

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