Ethernet-APL: Converged IP-Everywhere in the Field

Imagine, any time being able to connect an additional sensor, video camera, infrared thermal camera, on-off valve, HMI panel, or a package unit controller anywhere in the plant with just a short 2-wire patch cord to the nearest junction box in the process unit. Today such devices use different signals: 4-20 mA, VBS video, Cat 5 Ethernet, on-off, Modbus/RTU, and Profibus-DP etc. connecting to different signal wire infrastructure which may not be close at hand making deployment of additional devices a challenge. With the future Ethernet-APL all these kinds of devices can share the same Advanced Physical Layer (APL) network infrastructure; ubiquitous across the plant making additional deployments easy. So what does APL mean for the next generation of plants? Here are my personal thoughts continuing from the earlier Ethernet-APL essay:

Mixed Signals

Today every plant unit has a plethora of different signals in heterogenous wiring infrastructures: 4-20 mA (in, out, 2-wire, and 4-wire), on-off (in, out, dry contact, AC, DC, and many more), Modbus/RTU, Profibus-DP, VBS video, Ethernet (Cat 5), plus 24 VDC. There may even be multiple Modbus/RTU networks for each vendor as Modbus/RTU devices tend not to share the same network. Building 5 or more signal infrastructures for the plant is complex and costly: cables, cable tray, and junction boxes. Since many of these signal types are not intrinsically safe, explosionproof / flame proof installation is instead required which is costly.

Similarly, deploying additional devices in a plant years later is also costly. In many cases the required signal infrastructure may not be available in the vicinity so if you want to deploy for instance an infrared camera for leak or spill detection, an advanced sensor, or a gas analyzer, the right signal infrastructure has to be extended such that VBS video signal, Modbus/RTU, or whatever can be backhauled to wherever it needs to go.

Office Ethernet Example

In the office, Ethernet has slowly taken over not only the computer networking between workstations, servers, and multi-function printers etc., but also the phone system, CCTV security cameras, video conferencing system, and even the video wall etc. A single signal infrastructure for all kinds of office devices and systems.

Deploying additional office devices is easy as they share the same Ethernet infrastructure.

This sets an example for what Ethernet in the field could be like.

Ethernet-APL for the Field

Most control systems already use regular Ethernet (Cat 5) in the marshalling room and control room for I/O subsystem, controllers, servers, and workstations. Regular Ethernet is not suitable for the field, so therefore Ethernet-APL will be used in the field instead. The vision for Ethernet-APL is a converged IP-everywhere network; where process units only require a single simple wiring infrastructure where data from all kinds of devices share the same single Ethernet-APL infrastructure. The expectation is that Ethernet-APL will take the place of everything in the field for new plants, in place of the mixed signals of the past, just like Ethernet took the place of everything in the office. That is, control, safety, monitoring, video, and power on the same two wires: a single multi-purpose network. This will result in savings, particularly with intrinsic safety. And it becomes easy for I&C engineers to add all kinds of devices as an afterthought any time in the future as the Ethernet-APL infrastructure will be ubiquitous across the plant so there will always be an APL field switch somewhere nearby where you can connect. This vision mimics the IP-everywhere Ethernet convergence we have seen in the office. This ability to easily add-on sensors and other devices is key to digital transformation, digitization, digitalization, Industrie 4.0, Industry 4.0, the Fourth Industrial Revolution (4IR), or whatever you prefer to call it.

That is, sensors, video cameras, infrared cameras, on-off valves, HMI panels, and small controllers in the field will all be IP devices. When everything is an IP packet it can all share the same Ethernet-APL infrastructure. A single infrastructure for all kinds of devices in the field. A reduction from 5 or so different kinds of hardware infrastructures down to a single hardware infrastructure will result in savings. Shared cables, junction boxs, and marshalling.

Non-Exclusive

For traditional bus protocols like Fieldbus, Modbus/RTU, Profibus-DP, and HART etc. the network is exclusive; all devices are FOUNDATION fieldbus, all Modbus/RTU, or all are Profibus-DP. Never a mix on a network.

Ethernet, and therefore also Ethernet-APL, is different. It is non-exclusive, meaning there is a mix of application protocols in use. That is, there is a mix of devices communicating FOUNDATION fieldbus HSE, HART-IP, Modbus/TCP, and PROFINET-IO communicating at the same time. Many devices supporting multiple protocols; serving multiple applications at the same time using different protocols. And not only that, there will be many devices using non-automation protocols at the same time. Digital video cameras use Real-time Transport Protocol (RTP) or Real Time Streaming Protocol (RTSP). That is, there is no PROFINET video camera or HART-IP infrared camera, but a video camera or infrared camera will be able to share the same Ethernet-APL network as PROFINET-IO and HART-IP devices. You probably would not put perimeter security video cameras on APL, but APL video cameras may be used for process video like flare monitoring, reading drum labels, rotating kiln, and incinerator operation monitoring. That is, a mix of devices, providing a mix of data, using a mix of application protocols will share the same Ethernet-APL network. That is, many of the new innovative devices you will see on an APL network will not be HART-IP or PROFINET-IO, devices but they all share the same network.

So all devices on the network need not use the same protocol. Not even all the instrumentation. A transmitter using HART-IP and a valve using PROFINET-IO can be part of the same control loop, but the controller in between must be able to handle both protocols.

Virtual Marshalling

Note that not all the data on the APL network is communicated to the DCS or the historian because not all devices are related to process control. Process control data goes to the DCS. But, for instance, video does not have to go to the DCS or historian. Video packets will likely go to a Video Management Software (VMS) or a simple Digital Video Recorder (DVR) – and it may go to DCS operator workstations or video wall from there. That is, packets are switched to the DCS, historian, VMS, or other destination.

The network management for the Ethernet-APL network must ensure bandwidth is managed to make sure latency is not introduced for process control and safety functions.

Next

Learn more about APL from the Future of Device IO: APL Single Pair Ethernet essay.

Plants are already being designed to use Ethernet-APL even though devices are not yet available. If you are designing a plant right now, it may be a good idea to investigate using Ethernet-APL as the converged IP-everywhere signal transmission for the field. Well, that’s my personal opinion. Do you see APL as single infrastructure, or do you prefer multiple separate infrastructures? If you are interested in digital transformation in the process industries click “Follow” by my photo to not miss future updates. Click “Like” if you found this useful to you and “Share” it with others if you think it would be useful to them. Save the link in case you need to refer in the future.