Choosing a plc and overall control strategy

[JesperMP]

Definitely go for a bussystem.
The control system is already arranged in separate panels.
The PLC will be slightly more expensive, but you save a lot of new cables, and terminals, and work hours.

Every person has his own favourite. Mine is Siemens ET200S i/o connected via Profibus or Profinet, with a 315-2PN/DP CPU or a IM151-8 CPU.
IM151-8 + ET200S via Profinet is quite inexpensive, and I think it is performant enough for your application.

It looks like the fastest event on the distributed i/o would be a proximity sensor that is on about 3-4 ms and would need to be reliably detected.

That means you need a deterministic i/o update around 1-2 ms, or use a counter module if it suits the application. 1-2 ms is not ultrafast but also not entirely trivial.

On a previous controller replacement we went with a Beckhoff system, their support was good and their North American headquarters are near to us.

Sounds as if that is the way to go. You already have experience with Beckhoff and it works OK for you - to switch to another brand should be for some really compelling reason.
And Ethercat is very fast too.

 

[MikeW]

I have installed Ethernet in multiple plants always islanded from the IT networks. As of yet, I have not run across any issues with IT trying to take over.
I guess I am lucky so far.

Yep, I recently ran into problems from our bean counters when I proposed to connect all our control islands, "You want to run a separate Ethernet line for a control network, what's wrong with the existing network that's installed? Seems like an unnecessary expense since we already have the company WAN in that area". In this case, IT agrees that a separate one is necessary but they don't want to be responsible for it or any of the control PCs. IT does like to have uninterrupted sleep during the night.

 

[iant]

I'll throw my 2 cents in
Look at the programming software
1. License costs - per package
2. On going support cost per Package
4. update costs for software
5. No' of packages to build an integrated system
6. Access to internet - Optional or mandatory

this will take you away from a popular industry brand.

it is like buying a printer for $50 then paying $100 for a black cartridge every 50 sheets



Ongoing costs are