Fieldbus vs XML Message

Believe me, I know there is a HUGE difference in the types. However, I need a clear way to explain to C-Level types what the benefits of using Fieldbus are. We have a conveyor processing up to 4 or 5 boxes per second. We have two systems, one moving the boxes, another system apply some process to the box. This "process" needs to know in real-time, the type of box in order to set up process and collecting information for each box. These guys seem to think that we can have a central server collecting information from the conveyor using <SOAP> (XML) and then send it to the processing controller.

Explain to me in C-Level (non-engineer) terms, why the benefits of Fieldbus in this application.


Edit: Additionally, we will likely need many pieces of information from this conveyor system.

ahuberee said:

Believe me, I know there is a HUGE difference in the types. However, I need a clear way to explain to C-Level types what the benefits of using Fieldbus are. We have a conveyor processing up to 4 or 5 boxes per second. We have two systems, one moving the boxes, another system apply some process to the box. This "process" needs to know in real-time, the type of box in order to set up process and collecting information for each box. These guys seem to think that we can have a central server collecting information from the conveyor using <SOAP> (XML) and then send it to the processing controller.

Explain to me in C-Level (non-engineer) terms, why the benefits of Fieldbus in this application.


Edit: Additionally, we will likely need many pieces of information from this conveyor system.

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The simple version is that they can go hand in hand, and they solve different problems: deterministic cyclic data and acyclic data.

You need a fieldbus to communicate cyclically between the PLC and the IO. This communication often needs to be fast (low latency, every 10 ms or less), but each message is a small amount of data (Less than 100 bytes). You also need to know quickly if the communication is failing. Part of it also is simply inertia, it's what everyone does. Have you ever heard of a drive or an IO block supporting SOAP directly?

Acyclic methods (like SOAP), allow you to collect large amounts of information on an as needed basis. You might only need to grab data every 10 seconds, but it might be 10,000 data points.

Focus on the determinism, the high update rates, and possibly also failsafe rated data (do you need to share e-stops between machines?). Depending on what you're doing, though, it might work with an IT protocol like SOAP or OPC as well. It just depends how often you need to talk.