At our recent General Assembly Meeting, we had attendees from very different kinds of plants. This setup some very interesting discussions and some interesting feedback on the meeting survey. On the complex side we had Ford, Audi, and VW plants, and an AGV-based amusement park ride. On the simple side we had an SI who specializes in smaller manufacturers.
The SI said he always uses unmanaged Ethernet switches. I always say “You will use a managed switch, or wish that you had.” But I think the SI and I are both right. Because I also say “There’s never a substitute for doing the engineering.” The SI knows his customers and their capabilities. His “simple” projects were going into plants that had no engineering department and the most highly trained maintainer might have an Associate Degree. I understand why he kept it simple.
The complex plants used managed switches. They had engineering departments and highly trained maintainers. They could avail themselves of the additional information from managed switches. That information allowed them to avoid downtime which is very expensive for them.
In the simple plants I would have liked to see managed switches and some HMI screens to take advantage of the data from them. But cost is a legitimate design parameter. It has to be considered when doing the engineering. This reminds me of my corollary to “You will use a managed switch, or wish that you had.” The more expensive downtime is, the more you should consider a managed switch.