A Control Design reader writes: As brownfield facilities look to add data-retrieval or -analysis capabilities to their equipment, many of them are looking at power over Ethernet (PoE) as a means to charge and run sensors or edge devices. As an integrator that builds, installs and modifies equipment, this can be tricky, depending on the existing network. Copper Cat. 5e cable is one thing, but a fiberoptic network has its own set of challenges. And the hybrid networks, not to mention the increasing number of wireless applications, create even more variables.
First, does anyone have advice for making a copper-versus-fiber recommendation to plants and factories? And what is being done in those instances involving fiberoptic cable or even wireless devices? What sorts of adapters or switches are available?
How do we enable these digital transformations, given the available technology?
Answers
Application guides infrastructure
The decision to use wireless versus fiberoptic versus shielded and encased copper wiring in a plant is heavily dependent on the specific application. Each Ethernet-capable physical layer offers strengths and weaknesses that make the combined usage an optimal solution for a facility’s network infrastructure.
Fiberoptic cable offers the advantage of very high speed, lack of signal degradation over long distances and immunity from electrical noise. Therefore, fiberoptic cable has proven to be an ideal physical layer for backhaul network segments that are transporting data aggregated from thousands of devices over multiple-kilometer distances.
Fiberoptic can also provide a way to transport critical data in plants that have high amounts of electromagnetic interference. Additionally, fiber can solve for hazardous area applications, although a battery or power cable is still required for the device. While batteries are a simpler initial solution, they present an ongoing maintenance concern that must be managed for the life of the device and are limited to lower-power devices.
The higher cost and complexity of fiber relative to other solutions has made this technology most appropriate for use cases when very large amounts of data, long distances or extreme electrical-noise/hazardous-area concerns are present. Note that, if both speed and distance are increased with fiber, the resulting performance gains are more modest; there is a tradeoff associated with distance and throughput.
Wireless communication is a very flexible means to connect different devices across a plant since the time and cost of running physical cable isn’t necessary. Wireless can also solve for longer distances, moderate electrical noise and hazardous area concerns. However, wireless devices still need either a physical power cable or a battery that requires ongoing maintenance effort and limits the total power of the device.
Recent solutions such as private and public 5G for industrial applications and Wi-Fi 6 have greatly increased the speed and therefore suitability of wireless for automation.
The advent of automated guided vehicles (AGVs) has also presented an opportunity for wireless to enable vehicles to travel throughout a facility without a fixed track (Figure 1). In fact, AGVs have recently revolutionized the assembly line. What was once a fixed path has now become flexible, as evidenced by the large wireless AGVs transporting the new Ford Lightning down the final assembly line in Dearborn, Michigan.
The largest challenge for wireless is that the network must be properly planned out to ensure that the appropriate performance is achieved. In industrial environments, wireless networks are challenged by disturbers—items that reflect or block wireless transmission—and absorbers—items that swallow up the wireless signal.
A site survey is necessary to ensure that the distances, obstacles and interference are taken into consideration relative to the needed traffic rate, latency and power consumption. Facility construction and layout will heavily influence the setup of a wireless network, given that varied surface finishes and geometries reflect and dampen radio waves differently. During the site or walk survey, wireless equipment should be placed and/or moved around the site to measure signal strength based on the location and number of the wireless devices.
Usage of wireless is growing in industrial automation, given the increased speed and delivery options. However, it’s important to understand the performance needs of a specific application relative the constraints of a facilities layout, construction materials and electromagnetic interference to ensure a successful outcome.
Shielded and encased copper wiring has been the go-to solution for industrial-automation applications given the high number of options that can fit different performance and budget needs. Copper wiring can provide both communication and power, function over a variety of distances with field-installable connectors available for custom cable lengths, offer varied speeds of up to 1 Gbps, can be shielded to reduce electromagnetic interference and can run on low power for hazardous areas. Additionally, copper can accommodate movement in conjunction with flexible cable trays and can even provide the approximate distance of a cable break by measuring resistance.
While fiber and wireless can offer better performance in specific applications such as requiring long distances and flexibility, respectively, copper wiring is still the most versatile overall solution for field-device and automation connectivity in a plant.
Innovation is still taking place with copper wiring as well with single-pair Ethernet (SPE). SPE is one twisted pair of copper wiring that can support Ethernet at a low cost, which is allowing for simple devices such as contactors and push buttons to be connected to the network. SPE enables digital commissioning and diagnostics that allow for quicker troubleshooting and increased visibility into a plant’s operation.
SPE encompasses 10BASE-T1L general-purpose SPE applications, 10BASE-T1S in-cabinet applications, 10BASE-T1L Ethernet-APL applications and many more Institute of Electrical and Electronics Engineers (IEEE) SPE standards in addition to what is mentioned here.
Ethernet-APL is particularly notable since it is an intrinsically safe (International Electrotechnical Commission (IEC) TS 60079-47) two-wire extension of 10BASE-T1L SPE (IEEE 802.3cg-2019) designed for the process industries. Ethernet-APL allows for power to field instrumentation and long cable runs of up to 1,000 meters, as well as potential reuse of type A fieldbus cable (IEC 61158-2), and up to 10 Mbit/s communication speeds (Figure 2).
As another physical layer for Ethernet, Ethernet-APL provides seamless connectivity from field instrumentation to the plant-wide Ethernet to help enable digital transformation. Additionally, process instrumentation can easily communicate multiple variables such as temperature, level and flow from one instrument via the increased bandwidth of Ethernet-APL.
Steve Fales / director of marketing / ODVA
Hybrid connections
While copper and fiber both provide network connectivity, they each have characteristics that make them better-suited for different situations. Therefore, deciding which one to use in a plant or factory is seldom a question of one versus the other and more often a question of which one to use in which parts of the plant or factory.
Copper Ethernet cabling is typically more affordable, durable and readily available than fiberoptic cabling. Fiberoptic connectors are also more susceptible to signal degradation from dust and moisture. These factors make copper cabling the default option for most installations. Fiberoptic is best used in situations where a limitation of copper cabling needs to be overcome.
The maximum length of a twisted-pair Ethernet cable is typically 100 meters. If you need to connect two nodes that are separated by more than 100 meters, then fiberoptic cabling, or potentially a wireless option, must be used.
Fiberoptic cables offer another advantage in plants and factories: they are nonconductive and therefore immune to electromagnetic interference (EMI). Electric motors, welders and power lines are just a few potential sources of EMI in an industrial environment. Copper cables can conduct EMI, which leads to signal degradation. Two ways to mitigate this issue are to use fiberoptic cables or shielded copper cables. If shielded copper cables are used, care must be taken to ensure proper grounding.
Fiberoptic technology can provide a lot of bandwidth over long distances. This has led to increased adoption despite the higher installation cost compared to copper cabling. Many cities and facilities use fiberoptic cabling to build their network backbones. Fiber is also finding its way into more industrial applications. In response to this, many switches and routers designed for industrial applications now include fiberoptic interfaces.
The number of wireless devices has exploded in the past decade. To accommodate this, wireless standards organizations have released updates to their protocols. These updates have resulted in wireless protocols that offer more bandwidth, better resistance against wireless interference and improved security. Manufacturers of both wireless access points and end devices are releasing products that utilize these updated standards. Although the reliability of physical wiring continues to make it the default option for industrial networks, wireless protocols are reliable and secure enough to be used in a number of industrial applications.
When it comes to adapters or switches for copper, fiberoptic and wireless, there are typically three options: switches/routers, converters and access points. There are many switches and routers that offer both copper and fiberoptic connectivity.
When there is a need to convert from one connection type to another mid-cable, a converter is needed. There are many copper-to-fiber converters on the market. Converters can be a good option for situations when a fiber connection needs to be converted to a copper connection or vice versa away from a switch or router. For example, a fiber converter can be used when an end device that only has a built-in copper interface is more than 100 meters away from a switch or router, requiring the use of a fiberoptic cable. In this case, the converter is used to connect the copper-only end device to the fiber cable.
Wireless access points are used whenever a wired network needs to be bridged with a wireless network.
The first step of any network upgrade is performing an analysis to determine what is needed. A lot of questions need to be answered before resources and time are invested into any network upgrade. Will wireless devices be used? If so, wireless access points will be needed. Will any power over Ethernet (PoE) devices be used? If so, PoE switches or injectors will be needed. Are there any instances where fiberoptic cabling will be needed? Runs beyond 100 meters in length and areas with high electromagnetic interference are examples of places where fiber should be considered. If the environment is subject to extreme temperatures, equipment designed to operate in those temperatures will be necessary. Only through proper analysis can any kind of digital transformation be enabled.
Chris Burg / product manager / Pepperl+Fuchs
Match network topology
Copper versus fiber is mostly a question of bandwidth and distance. If you are 300 feet or less, then 1,000 Mbps with copper is easier to scale and quicker to install and can prove PoE, if desired.
Fiber makes for a longer install time but will allow for gigabit Ethernet and long-range runs when necessary.
Wireless is a different beast that really needs to be thought about before use. Bandwidth on wireless is low, and transmission speed is limited. It also can be unreliable if there is an abundance of different networks. Several manufacturers make wireless-to-wire adapters, which allow one to use an IT network to connect OT stranded assets into a reporting system without running wires, as long as bandwidth and safety are not an issue.
Fiber-to-copper adapters are available from most major suppliers to allow the transition of long runs into the machine, reducing the need for stepping through several switches to buffer copper-only signals across a facility.
Ultimately, to enable the transition into a digital system, one needs to identify some key aspects. What are the assets to be connected, what connection protocols are on these devices, are protocol converters needed, what are the bandwidth needs, and what are the distances? After you get these nailed down you can figure out the physical layer that best fits the topology.
Mark Russell / tech application support manager for the Americas / RS
Combine old with new
The points you make regarding the challenges of existing infrastructure and new technology adoption, which we encounter daily, resonate with us. Consider plant-floor physical-network deployment with a structured cabling approach aligned to industrial automation and control system (IACS) logical architectures, such as International Society of Automation (ISA) 95 and Purdue model, and to IT standards and industrial premises, such as American National Standards Institute (ANSI)/Telecommunications Industry Association (TIA)-1005.
There are at least three common factors that play into answering copper-versus-fiber and recommendations for plants and factories: resiliency and performance, distance limitations and electromagnetic interference (EMI) noise.
The core and distribution switches of the network are often connected with fiber media as a default, ensuring overall network performance over long distances. Fiber media performance is up to 2,000 meters (1 Gbps) for multimode fiber and 70 kilometers (1 Gbps) over single-mode fiber, which you can picture traveling across a facility or even between facility buildings over a considerable distance.
It’s also very common for the access layer switches, serving production cells and machines, to use fiber connectivity or a fiber ring for resiliency and redundancy—providing quick switch recovery response avoiding downtime, ensuring uptime in critical production areas.
Copper can be considered for connecting switch to switch, but it is not common, mainly due to the factors you outline, where future needs of the network may outpace the performance capabilities of the selected copper media.
All that said, copper twisted-pair cabling by far is the most common Ethernet media used in the industrial network. In fact, most downlink connections to Ethernet devices are over copper media, and the distribution switches are actually placed to balance those copper media links so they do not extend beyond the standards limit of 100 meters. Cat. 6 and 6A cabling and components are growing at a fast pace, partly to futureproof digital devices, but also to address performance of IT devices such as wireless access points on the plant-floor network.
Cat. 6/6A also supports four-pair power over Ethernet (4PPoE) or Institute of Electrical and Electronics Engineers (IEEE) 802.3bt Type 4 devices and up to 100 W.
Cat. 6A cabling, with its good signal-to-noise performance and several shielded versions available to choose from, typically will address EMI. In some cases, in extreme environments with very dynamic EMI noise, such as a steel mill, fiber media does come back into play connecting devices, where fiber versions are available, and reducing or eliminating the chance for EMI noise.
The challenge is when to upgrade from Cat. 5e to Cat. 6/6A, and often that consideration is more than just cabling, and there is likely a need for a network assessment to create a physical network design plan. Assessment and design services for the physical network are becoming more common and available for plant floors.
And what is being done in those instances involving fiberoptic cable or even wireless devices?
Following the structured cabling model of a TIA-1005 system, designers commonly use enclosures called intermediate distribution frames (IDFs). These enclosures are the termination cabinets housing the fiber connections from the data center and can also house the fiber downlinks to access layer switches on production lines and the many copper downlinks to wireless access points. These IDF enclosures enable the network to be distributed zone by zone, aligning with logical architecture and providing a good structure for future additions.
DIN-rail-mountable patching devices are also available to adapt fiber connections in a common control panel for individual fiber adapters, fiber adapter panels and even fiber cassettes, which contain slack and protect the connections. Similar DIN-rail-mountable devices are available for copper downlink devices, as well. The use of these patch panels is a best practice, ensuring each link of the network can be tested during commissioning, so that spare connections can be made for future expansion providing faster troubleshooting and repair in the field.
Mike Berg / senior business development manager, industrial network infrastructure / Panduit
End-device interoperability
Recommendations for optical fiber between network switches in the industrial zone are generally tied to the following requirements: electromagnetic noise immunity, distance and outdoor cable runs. Of note, there is no option for power over Ethernet (PoE) available with fiber media, so that is another consideration that may be relevant in certain scenarios, for example, connecting wireless access points.
There are generally a couple of options specific to providing power via Cat. 5 Ethernet cable. These options are largely dependent on the types of end devices that will be powered via the network—for example, IP phones, wireless access points, cameras. The first option is to inject power via a switch that can support PoE options. The second option is to use a separate power-injector solution between the switch and the end device, which is common for brownfield situations.
There are industrial-rated options to support either scenario, PoE via Ethernet switches or injectors, particularly in the PoE+ catalog of end devices that need up to 25 W of power.
Classic PoE has not been widely adopted in industrial automation applications beyond network infrastructure such as access points. The reasons for this are well known, and the most recent technology, power over data line (PoDL) used in single-pair Ethernet, is expected to address them. There is still standardization needed to ensure interoperability in industrial environments—the Advanced Physical Layer work shared by ODVA, PI, FieldCommGroup (FCG) and OPC Foundation—but we expect this upcoming technology to drive digitalization further into field devices.
Paul Brooks / technology business development manager / Rockwell Automation
Data-transfer rates
The recommendation between copper versus fiberoptic should be based on the specific needs of the plants or factories looking to add data-retrieval or -analysis capabilities to their equipment. Consider the following key factors when making a copper-versus-fiber recommendation.
First and foremost, the decision should be based on the plant's or factory's specific needs, taking into account factors such as bandwidth requirements, distance, cost, reliability and futureproofing. Copper cabling is a low-cost option for supporting high data-transfer rates over short distances, whereas fiberoptic cabling provides high bandwidth and long-distance transmission while being immune to electromagnetic interference.
It is also critical to consider the existing network infrastructure and available technology when enabling digital transformations. Hybrid networks, wireless applications and fiberoptic cable all present unique challenges and variables. There are several adapters and switches available to help integrate fiberoptic cable into existing networks, including the standard/subscriber connector (SC), straight-tip (ST) connector, lucent connector (LC) and multi-fiber termination push-on (MTP)/ multi-fiber push-on (MPO) connectors, each with its own set of benefits and drawbacks. The connector selected will be determined by factors such as the type of fiberoptic cable used, the distance span and the application's specific requirements.
Furthermore, deploying fiberoptic networks requires significant infrastructure and installation costs, which can account for a significant portion of total project costs. The deployment method used, such as above-ground, underground or underwater, can also affect project costs and complexity.
Despite the costs, fiberoptic technology provides significant benefits in terms of faster data-transfer speeds, increased bandwidth and increased network reliability, making it a popular choice for organizations looking to modernize their networks.
When it comes to wireless devices, it's critical to ensure that the network can handle the increased data traffic and that the devices are properly secured. It may also be necessary to consider using power over Ethernet (PoE) to charge and power sensors or edge devices, which can simplify cabling and lower costs.
Ultimately, the best way to enable digital transformations in brownfield facilities is to consult with a professional cabling expert who can analyze the plant’s or factory's specific requirements and recommend the best cabling option and technology for the project. Plants and factories can successfully integrate new data-retrieval or -analysis capabilities into their equipment and drive digital transformation with the right expertise and solutions.
Daniel Weiss / senior product manager / Newark
