Is The Human Body Circulatory System Like an Ethernet Network?

I’m a scuba diver and always anxious to get to a warm weather location with crystal clear blue water. Because I’m a diver, I’ve spent a lot of time studying oxygen (for obvious reasons). I learned, for example, that the air we breathe is 21% oxygen and 79% nitrogen, the exact same concentration found in my scuba tank.

Every cell in our body needs that oxygen to function. The human circulatory system uses the bloodstream to carry oxygen to cells. The cells absorb oxygen and expel carbon dioxide waste. When that carbon dioxide reaches the lungs, it is expelled, and the oxygen from the air we breathe in is added to the bloodstream. Of course, there is more to the contents of our bloodstream than oxygen and carbon dioxide. The circulatory system carries all sorts of nutrients and hormones throughout our body.

In a way, this is very similar to an Ethernet control system. The bloodstream in the circulatory system is like the Ethernet cabling in the control system. The oxygen, carbon dioxide and nutrients in the circulatory system are the messages of EtherNet/IP or PROFINET packets.

Both systems carry vital information: The circulatory system carries the essential oxygen and carbon dioxide while an Ethernet control network carries the all-important control signals. If either is interrupted, the system dies quickly. If the signals can’t get through, the production system dies like a human body deprived of oxygen will die (only the production system can be resurrected).

Both carry less critical information: Besides oxygen and carbon dioxide, the circulatory system carries vital, but not urgent, nutrients. The human body can live for days without those nutrients. The Ethernet production control network also carries less critical information. There are many kinds of data in these less-critical messages, including energy data, authorizations and permissions, IoT application data, and much more. Just like the human body can survive for a time without the required nutrients and hormones, the production system can continue even if this other message traffic is delayed or canceled.

Both are highly repetitive: The circulatory system works continuously, 24/7, to move oxygen and carbon dioxide. A control network, like circulatory system, also works constantly, repetitively and cyclically to move critical control systems between devices interacting with the physical world and the controller.

Of course, there are differences. The circulatory system can carry oxygen, waste and nutrients simultaneously. Ethernet switches try to emulate this behavior by getting data from individual control devices simultaneously, but, in the end, it must go to the programmable controller sequentially. There is no multiple message delivery vehicle in Ethernet production control systems.

The circulatory system is also much more resilient than production control networks. The circulatory system is self-healing and able to manage wounds and foreign invaders. An Ethernet control network has no such ability. An unexpected network storm can destroy communications between control system devices and terminate the operation of the production system. Self-healing is far off in the future for control system networks.

In these situations, it is only possible to troubleshoot with a tool like the IntraVUE control system monitoring and auditing tool RTA just added to its portfolio. IntraVUE keeps a log that you can use to track down these kinds of problems.

Many data scientists who need machine data don’t understand how an Ethernet network is like a circulatory system and that critical data is essential. They must understand, develop, implement, support, and enforce those yet-to-be-defined mechanisms before requiring control system networks to convey IIoT data. They often don’t recognize the impact they will have on control system behaviors.

PS: Thank you to Gary Workman, who generated the initial concept for this article.