Migrating to Industrial Ethernet
For many people outside advanced manufacturing industries, any mention of the “shop floor” invokes mental pictures of loud, dirty and sometimes dangerous workplaces. But people on the inside of these industries know otherwise. Modern manufacturing is highly automated and conducted in clean, well-lit environments where safety is a foremost concern. They also know that behind this lustrous picture even greater innovations are coming that will further change how manufacturing’s done. One of those is data.
Data, especially in real-time, has transformational power. It can provide insights for better decisions, faster responses, greater efficiencies, simplified complexity and more production flexibility. The problem with data, however, is two-fold: its manageability and communications.
For years, Totally Integrated Automation (TIA) has made tremendous strides in addressing both these issues, with much greater visibility and transparency along manufacturing’s entire value-added chain. What’s more, the business ecosystem surrounding production has also experienced a data revolution that’s further boosted visibility and transparency.
An entire plant can be run remotely via an iPad. And products are leaving their factories with onboard sensors giving design and engineering functions real-time feedback that can help define and refine their next generation within weeks and months instead of years.
Yet data’s growing volumes, especially outside manufacturing, challenge a manufacturer’s ability to keep up. Data exchange from a variety of sources is starting to blend manufacturing with design, engineering, procurement, marketing and sales.
Today, an entire plant can be run remotely via an iPad. Factories are becoming smarter, monitoring production in real-time. This provides nearly instantaneous feedback, which can help define and refine their next generation within weeks and months instead of years.
To be sure, this blending goes far beyond a Walmart cashier ringing up a box of Pampers through a register – in effect, a data-entry terminal – that sends an EDI replenishment signal to Procter & Gamble. With technologies such as additive manufacturing and 3-D printing, we’ll see more and more mass customization as well as production at the point of use.
This is just a glimpse of manufacturing’s revitalization. It’s a new age that will accelerate reductions in cycle times and costs, boosting competitiveness and margins. It will undermine offshoring’s advantages by making the cost and time of transportation new considerations. And it will save energy and, ultimately, the environment.
Data is driving this transformation, which in turn generates even more data. Mountains of data. Much of it in real-time with a lot of its value being extremely perishable.
To address data manageability, tools are available to mine so-called Big Data for nuggets of information and insights, and those tools are becoming ever more sophisticated. To handle data communications more effectively – and with greater scale – industrial Ethernet such as PROFINET will accelerate the inroads it’s made into manufacturing over the past 15 years. It will replace aging field bus technology that continues to be serviceable but cannot keep pace with the changes going on all around it.
This white paper builds on that thesis. In the following sections, we compare field bus technologies with industrial Ethernet, provide a primer on what industrial Ethernet is, and then suggest some strategies to consider for implementing it. Our goal is to help you become better informed about industrial Ethernet, so you can determine a way forward that best suits your business.
1. Fieldbus and industrial Ethernet, complementary technologies
Fieldbus is a term used to describe a group of industrial networking protocols as defined by IEC 61158. These were commercialized in the 1980s and provide real-time distributed control of the components comprising an industrial system. Among these serial bus protocols are AS-Interface, BITBUS, CAN, Interbus, Modbus and PROFIBUS. Of these, PROFIBUS is most widely used, with over 45 million nodes worldwide as of 2013.
Ethernet, also commercialized in the 1980s, is a digital networking system but one originally designed to operate in near real-time. It has since been adapted for use in industrial data communications and control. At the same time, it’s become the world’s de facto networking standard for wired and wireless applications.
In fact, advancements in Ethernet over the years have minimized its latencies to such an extent – below human perception levels of 21 milliseconds – that it’s now used to transport voice and video in near real-time. PROFINET, one of several available industrial Ethernet technologies that we’ll look at more closely in the next section, has gone further to enable real-time communications for industrial uses with cycle times of less than one millisecond.
PROFINET: More efficient network traffic management
As plant floors evolve from fieldbus toward more open technologies such as Ethernet, questions arise about how to manage network traffic. For machine-to-machine communications, many solutions are available, but not all are created equal.
Traditionally machine-to-machine communications required an interface between the machines. That could be either software programming blocks that sent and received data. Or it could be a hardware device such a network coupler that acted as a slave to both machines through which data was exchanged.
Nonetheless, the traditional solution of machine-to-machine communication typically required manual communication block programming or the added cost of physical hardware to act as the interface.
PROFINET, however, simplifies this. With its iDevice (Intelligent Device) feature, a controller can map part of its process image table as addressable I/O for another controller. That way, a PROFINET system can have two controllers exchanging data without the need for programming or additional hardware.
The iDevice functionality is a simple check box and a table where inputs and outputs are mapped. Once a controller is configured as an iDevice, it can be assigned to another PROFINET controller as an I/O drop. All communication happens at I/O speeds, requiring less overhead and management than traditional TCP/IP traffic. The iDevice functionality eliminates the need to monitor and manage TCP/IP traffic and reduces the potential complexity of machine-to-machine communication.
Where do fieldbus and Ethernet technologies fit into the control hierarchy of complex, automated industrial systems? Both have long held respective roles: At the high level, the Human Machine Interface (HMI) communicates via Ethernet with a middle layer of PLCs, which in turn are linked via fieldbus technology to their various sensors, motors, switches and other devices.
Fieldbus has been widely deployed in industrial process control for two reasons. One is that a predecessor control
technology, known as 4-20 mA current loop analog communications, required dedicated wiring between devices. This got expensive and complicated quickly, as more devices needed control within industrial environments. The other reason is that a 4-20 mA connection, although much simpler, could only transmit one parameter while fieldbus could communicate several.
To be sure, fieldbus technologies continue to serve their functions adequately, but a large number of industrial control requirements have risen that are beyond fieldbus capabilities.
- Wireless and fail-safe communication
- More than one master in the same bus section
- Web-based management
- Redundancy through ring topology
- More than 126 connections/nodes on the same bus
- Graphical visualization and automatic topology detection
- Very high transmission rates over long distances, withoutseparate repeaters, and without concerns about speed, adaptation, reflection and data collisions
- Transmission of large data volumes such as databases, images and files via the same cable
- Easy energy management
- Complete access to the entire network, includingremote access
Ideally manufacturers can leverage the industrial experience of fieldbus deployments with the openness and flexible options of industrial Ethernet. That’s what PROFINET does. With it, manufacturers that are currently operating in all fieldbus or hybrid networking environments can simplify their networks, reduce their network maintenance costs, and gain greater flexibility in configuring and adapting them to new processes and requirements. They’ll also realize virtually limitless scalability in the number of PLCs and network devices their networks can support. This will lay the foundation for taking part in the world’s data-driven manufacturing renaissance and sharpening their competitive edge at the same time.
2. Industrial Ethernet: PROFINET, the best of both worlds
Industrial Ethernet refers to the use of standard IEEE 802.3 Ethernet for automation and process control in manufacturing environments that may be subject to temperature extremes, dust, humidity, vibration, electromagnetic interference and other harsh conditions exceeding the limits set for most information technologies. To adapt Ethernet for these environments, equipment makers “ruggedize” their switches and connectors, while deployments often specify optical fiber cabling to shield signals from ambient electrical noise.
Advantages of industrial Ethernet include:
- Increased speed, from 9.6 Kbit/s with serial connections to 1 Gbit/s with Gigabit Ethernet
- Increased distance and wireless capabilities
- Greater precision with less complexity
- Compatibility with standard access points, routers, switches, cables and optical fiber
- Greater scalability by having more than two nodes on a link
- Consumer-provider architectures, replacing masterslave ones
- Topology options, including Ring, Star and Tree topologies
- Better interoperability
- Remote access options
PROFINET is the world’s leading industrial Ethernet protocol with almost five million nodes in operation. It uses Ethernet’s TCP/IP standards for non-time critical communications, like diagnostics, but adds deterministic real-time channels to achieve real-time communications in as little as 31.25 microseconds. Specifically, PROFINET offers scalable communications in three modes:
- TCP/IP, for non-time critical applications, with reaction times of up to 100 milliseconds
- Real Time (RT), for real-time transfer of time-critical process data, with reaction times of less than 10 milliseconds
- Isochronous Real Time (IRT), for motion control applications, with reaction times of less than 1 millisecond
Users of industrial Ethernet in general and PROFINET in particular can realize greater productivity in several ways. One is by way of more flexibility, using wireless PLCs and mixing topologies, to tailor plant layouts for optimal output instead of having to adapt output to plant layouts. Another is greater efficiency, thanks to standardized cabling and plug-and-play parts and energy savings. The third is improved overall performance, given faster transmission speeds, much larger data packets, and greater precision control.
“Doing nothing” is not an option
Why? Because standing still has its own opportunity costs
Another PROFINET benefit is up to 50 percent less downtime when errors occur. That’s because device, network and process error alarms are transmitted within milliseconds from the device to the controller. Resets can be programmed to trigger automatically if errors are minor. For major ones needing human intervention, remote diagnostics can be done and remedies implemented via tablets and smartphones. This contrasts with time consuming diagnostics requiring much more manual interventions that can cost thousands of dollars an hour when production lines are stopped.
Importantly, PROFINET also integrates with existing fieldbus systems using a gateway/proxy concept. It is possible to integrate equipment using existing fieldbuses like PROFIBUS, DeviceNet and Interbus, without changes to existing devices, protecting legacy investments. That provides industrial engineers and plant operators tremendous flexibility in how they migrate to industrial Ethernet.
3. Practical migration strategies
Unlike other available fieldbus and industrial Ethernet technologies, PROFIBUS and PROFINET are interrelated to the extent that both are governed by PROFIBUS and PROFINET International (PI), the world’s largest automation community with over 1,400 member companies. At the same time, PI collaborates with many other industrial standards bodies to ensure compatibility and interoperability.
The kinship between PROFIBUS and PROFINET goes deeper than their names and PI’s oversight: PROFINET leverages PROFIBUS technologies with care to ensure migration can occur smoothly and without significant costs in components or production downtime. To deploy PROFINET, the following three approaches depend on the situational environment:
- Greenfields: These deployments are easiest, of course, because no legacy infrastructure needs consideration and accommodation. A production process can be completely tailored to achieve optimal results, then quickly reconfigured in response to the demands of new opportunities or requirements.
- Step-wise migration: To conserve legacy fieldbus investments, plant operators can choose to upgrade one part of a facility at a time, perhaps during seasonal slack times, during cyclical down times, or when retooling. This avoids potentially expensive disruptions to plant production, and project management is much easier.
- Rip-and-replace: For fieldbus infrastructures that have clearly outlived their utility, this approach may be appropriate. Although inherently disruptive, plant operators will gain Ethernet benefits immediately. Similar to a step-wise migration, rip-and-replace migrations obviously are best done during plant downtimes.
One of the most important factors in successfully migrating to industrial Ethernet, whether PROFINET or another such technology, is the team in charge of the project. It has to empathize with a fieldbus culture that may prefer to leave that infrastructure in place, while selling the vision not only of the Ethernet migration but also of how that will enable the plant – and all employees – to take part in the manufacturing renaissance now underway around the world.
4. Why “doing nothing” isn’t an option
For many manufacturing and industrial facilities, now is the best time for migrating to PROFINET. Why? Because standing still has its own costs – opportunity costs – that grow larger and compound with each passing day. Of course, that point gets amplified whenever a production line goes down and has to be troubleshooted manually while output and customer shipments wait for it to be fixed.
As a technology, PROFINET is mature and proven in thousands of customer applications spanning just about every production industry, from aerospace to mining to food processing. More and more devices with PROFINET connections are continually expanding the range of applications across all industry sectors that offer more operational visibility, flexibility, efficiency and performance.
PROFINET is a key enabler of manufacturing’s data-driven transformation. With it, manufacturing gains a single network for I/O, process instruments, motion controllers and functional safety. And it’s all integrated within the IT environment for top-to-bottom, stem-to-stern enterprise transparency on and off the production floor.