Specifying Industrial Ethernet Cables for Optimal Performance

Industrial Ethernet is an important technology that can replace slow, fragmented legacy networks with a high-speed, unified communication backbone and deliver real-time determinism. There are numerous factors to consider related to robust cabling performance when deploying industrial Ethernet. One of the first decisions relates to network speed vs. distance expectations.

Applications that require up to 100 MHz bandwidth and 1 Gbps speeds over up to 100 meters need Cat 5e cabling. Cat 6 delivers more speed and longer reach; supporting up to 250 MHz bandwidth, handling 1 Gbps up to 100 meters, and reaching 10 Gbps speeds over shorter runs up to 55 meters.

The next decision, with even more degrees of freedom, is where and how the network will be deployed and the resulting performance and environmental demands. Does the application require shielded cables? What about extreme temperatures, high vibration, and exposure to oil, gasoline or chemicals?

Will the cable be placed outdoors or require to be Mine Safety and Health Administration (MSHA) approved for mining and harsh environments? What about demands for safety and reliability inside or adjacent to high-voltage equipment like industrial motor control cabinets and handling extreme electromagnetic interference (EMI) conditions?

Framework for Ethernet cable selection

Belden has developed a structured framework designers can use to sort through the complexities of DataTuff industrial Ethernet cable selection to quickly and efficiently arrive at an optimal solution for specific application scenarios.

The initial consideration is data rate requirements. Applications like IoT sensors and standard IP cameras need 10 Mbps to 100 Mbps. High-resolution IP cameras and controllers using protocols like EtherNet/IP, PROFINET, and Modbus TCP require up to 1 Gbps. Heavy trafficked backbone cables often demand 10 Gbps connectivity.  When up to 100 Mbps is needed, Belden recommends 2-pair Cat 5e cables. For up to 1 Gbps, designers should turn to 4-pair Cat 5e, and for up to 10 Gbps, Cat 6a cables.

Next, it requires a clear understanding of the flexing and environmental factors that the cable will need to withstand. That dictates the basic cable materials and structure. For example, in low vibration environments inside cabinets or control rooms, a solid conductor design can provide the highest consistent bandwidth.

Moderate vibration in locations like factory floors can benefit from cables with Bonded-Pair construction (detailed below). They also need materials that can withstand exposure to a variety of challenges including oil and chemicals, rough handling, abrasion, wider temperature variations, and electromagnetic interference while still delivering reliable connectivity.

High vibration can be experienced by cables directly connected to industrial robots and other machines. That can make Bonded-Pair construction even more important.

The third consideration is jacket options for providing the necessary level of protection to ensure reliable performance. This article presents several of the most demanded options. The overall DataTuff line includes comprehensive jacket choices including:

• PVC, polyethylene, FEP, FRNC/LSNH, PUR, or TPE
• Heavy duty, double jacketed, or aluminum armored
• Halogen-free or low smoke zero halogen jackets
• Versions are also available for burial or outdoor use, with gasoline resistance, and for use in unusually high and low temperatures

Finally, inside the jacket, there’s the choice between a shielded or unshielded cable. The DataTuff industrial Ethernet cable line offers several options. For low-interference areas, unshielded (designated U/UTP or UTP) cables can provide limited, but appropriate, noise immunity.

In locations with moderate EMI control, foil shield (F/UTP) cables have 100% coverage using aluminum/polyester tape wrapped around the core bundle along with a tinned-copper drain wire. When maximum immunity is needed against both high-frequency and low-frequency interference, cables with combined braid and foil shields (SF/UTP, or foil + TC braid) can be used. They combine an inner 100% foil shield with an outer tinned-copper braid shield (typically 70% coverage), and a drain wire.

Figure 1: Key construction details of four examples of industrial Ethernet DataTuff cables from Belden. (Image source: Belden)

Bonding benefits

Belden’s patented Bonded-Pair cable construction is used on most DataTuff cables. It connects the conductor insulation of cable pairs along the longitudinal axes to enhance return loss (RL) performance for specifications like ODVA for EtherNet/IP. The cables are suitable for use with the Common Industrial Protocol (CIP) to implement automation extensions like CIP Safety, CIP Security, and CIP Motion.

Using Bonded-Pair cables in high-vibration and flexing applications can deliver enhanced performance including maintaining constant and uniform conductor-to-conductor spacing that delivers better and more consistent electrical performance including lower return loss (RL) and improved signal quality (Figure 2). The uniform centricity is maintained even after bending, twisting and pulling when installed and during operation.

Figure 2: Belden Bonded Pair technology (right) delivers consistent concentricity between conductors along the entire length of an Ethernet cable compared with non-bonded construction (left). (Image source: Belden)

Proof of performance

Tests of Bonded Pair cables and nonbonded-pair cables have demonstrated the benefits on Cat 5e 350 MHz installations. The test simulated the pulling and bending cables experience during normal installation processes. It compared return loss (RL) performance of the cables as they came off the reel and after the installation stress procedure.

RL measures the amount of signal reflected back toward the source due to internal impedance mismatches. Poor RL distorts data streams, increases packet error rates, and lowers overall data integrity.

Test results showed that the nonbonded-pair cable had an RL degradation over 12 dB while Belden Bonded-Pair Ethernet cables showed little to no change in RL performance.

Choices are good

Regardless of the application demands, Belden offers a suitable DataTuff industrial Ethernet cable option. For example, model 7930A is a basic design that uses four non-bonded, unshielded twisted pairs (U/UTP) and supports Cat 5e performance. Choosing part number 7923A also supports Cat 5e with an unshielded 4-pair using bonded-pair construction for better performance.

Belden 7919A Cat 5e shielded (F/UTP) 4-pair non-bonded cable and can be called “basic plus.” It’s designed for environments needing good EMI protection and features an overall Beldfoil® shield with a stranded tinned copper drain wire and a heavy-duty, oil- and UV-resistant PVC outer jacket. It is commonly used in mining due to its MSHA rating.

Cat 6 performance

Moving up to Cat 6 supports higher data throughput and better noise rejection in standard factory automation networks. The Cat 6 unshielded equivalent to the Cat 5e 7923A cable is model 7927A (for solid conductor applications) or 7972A (for flexible/stranded conductor applications).

Belden 7953A has the overall Beldfoil shield found in the 7919A. It provides Cat 6 performance with 23 AWG bonded-pairs, an inner PVC jacket, and an industrial oil/sun-resistant outer PVC jacket.

More challenges, more choices

It’s not just about data rates, environmental challenges can be a significant factor in many industrial installations, and DataTuff offers solutions. For example, Belden 7934A unshielded cable rated Cat 5e, features a twisted pair (UTP) solid conductor design. It’s built with a water-blocking polymer gel and a rugged, sunlight-resistant polyethylene (PE) jacket rated for direct burial.

If the cable will be installed in places like plenum spaces which experience extreme temperatures, part number 7928A delivers Cat 5e performance and can be a good choice. Its unshielded design features Bonded-Pair construction and both the internal conductor insulation and the outer jacket are made of Teflon-style fluoropolymer (FEP), delivering an operating temperature range of -70°C to +150°C.

For routing alongside power cables, 7958A is the Cat 5e sibling to the 7953A Cat 6 cable noted above. Both feature Bonded-Pairs, an X-Spline center membrane to isolate pairs from one another, an inner PVC jacket, an overall Beldfoil aluminum + polyester laminated shield, and a final outer industrial PVC jacket. Because of this dual-jacket configuration, they carry a 600 V appliance wiring material (AWM) rating for routing alongside power cables.

In addition to the compressive offering of industrial Ethernet cables from Belden, DigiKey offers specifiers a choice of Digi-Spool, continuous spools of Belden industrial Ethernet cables for large installations and cut cables in 500-, 100- and 50-foot lengths for maintenance, retrofits and smaller installations. Quick and simple termination of the cables is an equally important aspect of deploying industrial Ethernet.

Reliable, easy, and versatile terminations

Reliable, easy and versatile (REV) field termination of Ethernet cables is supported by Belden’s industrial REVConnect RJ45 connectors (Figure 3). The unique insulation piercing structure provides a reliable connection, and the ability to withstand harsh environments in the field ensures continued reliability.

Figure 3: Rendering of the front and back of a Belden industrial REVConnect RJ45 connector.  (Image source: Belden)

It’s easy since a single termination tool is used for cable prep and termination. It’s versatile with models for Cat 5e, Cat 6, and more. Plus, shielded and unshielded versions, an IP67 rated plug kit, and fixtures for DIN rail mounting.

Conclusion

Industrial network designers need a wide range of rugged, high-performance Ethernet cabling options. Belden’s DataTuff industrial Ethernet cables deliver what network designers need for varied and tough to support operational scenarios. DigiKey offers DataTuff cables in several lengths to fit the needs of specific installations and Belden’s industrial REVConnect RJ45 connectors can speed Ethernet installation and deployment.

Recommended reading:

1. Simplify Implementation of Single-Pair Ethernet Networking for Critical Time-Sensitive Applications
2. Connectivity – The Backbone of Sustainable Automation
3. How to Select Flat-Panel HMIs for Optimal Results in All Industrial Environments
4. How to Implement Hybrid Control Networks in Industrial Applications
5. How to Extend the Industrial Edge with SPE and PoDL