Profinet: Mediate the rift between control engineering and IT
Sadly, the rift between control engineers and IT staff is well known. This rift needs to be healed. Here is an attempt at mediation.
Message to control engineers: IT is not your enemy.
Message to IT: Ethernet on the plant floor is not like Ethernet in the office.
Message to control engineers
While IT does not understand the unique requirements of the plant floor or the industrial protocols that run there, they do understand cybersecurity and IT-oriented Ethernet protocols that are applicable to their world and yours. These are protocols developed in the IT world, but which you can leverage. These are protocols that allow diagnostic data to be extracted. This data can speed troubleshooting and even prevent downtime. Simple network management protocol (SNMP) and link layer discovery protocol (LLDL) are the foremost of these protocols. The former allows retry counts, bandwidth, and other useful data to be extracted and acted upon. LLDP allows network topology to be determined automatically.
Since Ethernet can support multiple protocols at the same time, SNMP, LLDP, HTTP, and Profinet (and some other industrial protocols) can all coexist on the same network.
Cybersecurity is not just isolating your network; it’s applying processes and procedures as well as technology. IT can help with both.
The environment, the need for speed and determinism, and the importance of uptime will be foreign to IT. You probably have one foot on the office carpet and the other on the concrete plant floor. You can foster that relationship with IT. You can start by explaining the differences in your requirements as set out below.
Message to IT
Ethernet requirements for the control engineer differ from yours in these ways:
- Speed: While email can arrive in seconds, control messages need to arrive in milliseconds or even microseconds.
- Determinism: Control messages must arrive in a predictable, repeatable time frame.
- The environment: Have you seen the atmosphere out there? There is oily vapor in the air. It’s hot and humid. And you can’t see the electromagnetic interference, but it’s out there too. It’s not at all like the air-conditioned office environment.
- Uptime: When the production line stops, the flow of money into the company stops. This is generally regarded as a bad thing.
How do industrial Ethernets handle things differently to account for these requirements? They take special steps to ensure timely messaging. They account for the environment by using devices and cabling that can survive in the harsh environment. They prioritize uptime.
Now that you recognize the unique requirements of the plant floor control engineers, you are in a position to help them keep the plant running.
How to work together
Meet in the middle, at a firewall. That’s a simplistic solution that is especially sensible in small plants. On the office side of the firewall, the network is the responsibility of the IT department; on the plant side, control engineering. But work together on network security.
Larger plants may need to have a separate plant IT department. Seed it with resources from both IT and control engineering.
Work together. Your company will be more successful when you do.
– Carl Henning is deputy director of PI North America, the organization that provides education about the Profinet Ethernet protocol and Profibus networks. Edited by Mark T. Hoske, content manager, CFE Media, Control Engineering, firstname.lastname@example.org.
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For additional information on the differences between office and industrial Ethernet, PI North America has a white paper available called "Profinet and IT."