The following discussion is part of an occasional series showcasing the ISA Mentor Program, authored by Greg McMillan, industry consultant, author of numerous process control books, 2010 ISA Life Achievement Award recipient, and retired Senior Fellow from Solutia, Inc. (now Eastman Chemical). Greg will be posting questions and responses from the ISA Mentor Program, with contributions from program participants.

Colin Greatwood has 5 years of experience as an application engineer in the automation industry. He currently provides engineering, product, and application support to include routine to moderately complex design or modifications to products; training and technical sales support to customers; and working collaboratively with sales representatives for Festo. 

Colin Greatwood’s Question 

I'd love to have the automation community chime in on industrial networking. Specifically, I have been trying to spin up on various networking options, challenges, troubleshooting, and, even more importantly the death/growth of specific protocols. I am looking for a practical view of what people think is going to grow, die, and/or stick around.

Obviously, PROFINET and Ethernet/IP are taking over in the ethernet-based factory automation space, but I have also been seeing EtherCAT becoming more prominent. As for PTP protocols, I am following the development and adaptation of IO-Link but am concerned by the ability to troubleshoot.

As for challenges and troubleshooting, I am interested to hear what troubleshooting tools people are using for the more prominent protocols. I like to use Wireshark, network TAPs, and various tools from Modbus for TCP and UDP troubleshooting over the ethernet hardware layer. I know that managed industrial network switches with port mirroring capabilities is another higher-end option, but I prefer the network TAP for its price point and simplicity. I am currently looking for IO-Link troubleshooting tools but can't seem to find anything. Outside of standard error messages that are a part of the IODD file and device setup, I have found IO-Link troubleshooting problematic. 

Greg McMillan’s Answer 

I am looking for others to offer their experience on challenges and troubleshooting. For the future, recent developments with Ethernet Advanced Physical Layer (Ethernet-APL) in conjunction with Single Pair Ethernet (SPE) are a gamechanger, enabling much more data and much faster communication with field devices in both directions. 

Trunk runs as long as 1000 m can be combined with spurs of 200 m. SPE’s maximum communication speed is 10 Mbits/sec, whereas Foundation Fieldbus is 31.25 Kbits, and HART is 1.2 Kbits/sec, offering the opportunity for much faster updates and much greater intelligence. Furthermore, APL and SPE offer an IEC 60079 Two-Wire Intrinsically Safe Ethernet (2-WISE) that is capable of being deployed with pre-existing Fieldbus Type A cabling for use in hazardous environments. 

“Any protocol that runs on Ethernet today can be used over Ethernet-APL, and that includes HART-IP and Profinet as well as EtherNet/IP and other industrial Ethernet variants once generally excluded from hazardous-area duty,” notes Andy Kravitz at Emerson. “As a technology, FDI and PA-DIM are designed to help lower the bar for pulling information from field devices. Given that Ethernet-APL increases the bandwidth to individual devices, we expect the combination of all these technologies will help drive customers to fully utilize the capabilities of our devices. This will enable field devices to easily integrate with every level of the process data ecosystem from the control system all the way to the cloud.” 

The result can be a convergence of Operating Technology (OT) and Information Technology (IT). Much more intelligence from the synergy of smart instrumentation diagnostics, data analytics, and first principal models via a digital twin can greatly increase automation system and process knowledge, plus open the door to inferential measurements of key process variables, most notably compositions particularly of recycle and product streams. 

For more on the opportunities, see the Control Global article, “Ethernet-APL ready for prime time,” and the Automation World article, “Industrial Ethernet Advances Broaden the Network’s Value Across Industries.” 

We are fortunate to have some guidance offered by Mark Nixon, Director in Research (R&D), and Tom Freiberger, Product Manager - Industrial Internet (R&D) from Emerson Automation Solutions. 

Mark Nixon’s Answer 

We are spending considerable time right now on HART-IP and NexGen (which uses OPC UA protocol and PA-DIM), working through data, status, and behaviors between the control system and the device (and sensor). 

Details such as signal and device status, failsafe operation at the device level, initialization handshakes between the control, and the signal at the device level were handled implicitly by Fieldbus and handled less-so by most of the other field communication standards. None of the Field networks (other than HART-IP) fully define security at the field network level, which is important as field networks are opened to non-control traffic. Redundancy is another topic, as is time synchronization and bandwidth allocation. 

Tom Freiberger’s Answer 

I do not have experience with IO-Link specifically, so I cannot speak to that protocol’s diagnostic tools. 

For much of my Industrial Ethernet troubleshooting, I like to start at the connection initiator, taking advantage of any diagnostics or logging it provides. The connection initiator is generally the best place to observe error responses, as you implied. Beyond that, network captures with Wireshark are my next best tool. The biggest problem with Wireshark is that it can sometimes require modification to the network to get the packet capture, either by physical modification to insert the TAP or switch reconfiguration for port mirroring. This can be a large issue for networks in production. 

When the troubleshooting reaches the network level, having managed switches is very important. At a minimum, their port statistics can help track down faulty cabling. Some switches, when paired with SNMP and other tools, can help visualize the network layout. This can be important for tracking down issues due to unexpected devices on the network, or when troubleshooting involves third parties like device vendors.