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COMMUNICATIONS & NETWORKS MEETING INDUSTRY’S NEEDS
Sean Vincent, FieldComm Group, explains how Ethernet- APL will accelerate digital transformation throughout the process automation industry, combining high-speed digital communications with support for the needs of industrial installations
hange comes slowly in the process automation industry. And a corollary to this is that the excitement levels about new technologies are similarly muted. With facilities built for 30+ year operational lifecycles, and the significant expenses associated with turnovers, operators and engineers have little opportunity to embrace all the latest and greatest new technologies. For this reason, many plants still rely heavily on 4-20mA and HART instruments along with a smattering of higher-bandwidth fieldbus devices to implement their core process control systems.
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A notable exception bucking the generally blasé attitude towards new tech is that the process automation industry is excited about a new Ethernet-based physical layer named Ethernet-APL. Users, suppliers, OEMs, integrators, and standards organisations are eager to take advantage of the benefits promised by Ethernet-APL for accelerating digital transformation. What is Ethernet-APL and how should users begin to deploy it?
The basics and benefits Standard Ethernet media has been widely adopted for industrial networks and automation communications. However, users, suppliers, and component manufacturers have long realised that for high-speed Ethernet communication to work at the field level for process automation instruments, a new physical layer would need to be developed to support unique industrial requirements. Principal amongst these needs is two-wire power using common cable types, data communications over those same two wires, long cable lengths, and the ability to deploy in
hazardous environments.
A consortium of standards organisation and suppliers formed, specifications were written, and chip manufacturers began developing silicon. By 2021/22 the initial work was completed, the technology launched, and products are now entering the market. Ethernet-APL is a 10 mbit/sec Ethernet physical layer that can be deployed in hazardous areas using well known FISCO installation procedures. Existing two-wire fieldbus cabling may be used to connect Ethernet-APL instruments to networking infrastructure. Ethernet-APL is NOT an automation protocol, rather it is an Ethernet network supporting many Ethernet automation protocols like HART-IP, PROFINET, and EtherNet/IP.
Three specific components The specifications define three specific components of an Ethernet-APL network: instruments, field switches, and power switches. A special class of device, known as a powered field switch, is also defined. A wealth of detail on Ethernet-APL can be found at the FieldComm Group website or the dedicated Ethernet-APL website. Ethernet-APL promises to speed the digital transformation of process automation in several key ways:
• Higher speed communications means that more data can be transmitted, more functionality and intelligence can be built into instruments, leading to better predictive maintenance and operational efficiency improvement.
• Ethernet based communication means 8 JULY/AUGUST 2023 | PROCESS & CONTROL
that a workforce of technicians and installers trained in IT technologies like TCP, UDP, IP, and similar will be able to install and maintain automation networks. This will lower costs and allow highly trained automation protocol specialists to focus more effort on better control and automation and less on maintaining the network. • Using Ethernet as the network communications transport enables non- traditional Ethernet-APL enabled devices to share the same cabling infrastructure with field instruments. Imagine for example, a video camera on the same network as a pressure transmitter.
Getting started
A big challenge for end users will be to begin to imagine the possibilities presented by Ethernet-APL technology.
Today’s process control architectures generally consist of instrumentation, connected to remote I/O modules which in turn use Ethernet backhaul to interface with core process controllers as well as asset management and engineering systems. Often there is a firewall between the process control network and other enterprise systems. For simplicity we’ve omitted this distinction in Figure 1 (above). Figure 1 shows a typical plant network along with some ideas for deploying Ethernet-APL. On the diagram there is a multi-port powered Ethernet-APL field switch, a remote I/O unit that supports Ethernet-APL and field instrumentation. The deployment is intentionally located in a “mildly” hazardous area, Zone 2 Div 2, and would be a good first
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