Multiple ESM's
Looking through the documentation, I couldn't find a good explanation of how 2 different ESM's would interact. Everything I have seen only shows tasks within one ESM and one GDS. Is one ESM completely separated from the other? I cannot have the same task name in both, so there seems to be some overlap. Is it as simple as splitting tasks between them and letting the OS manage timing and priorities so the user can think of it as "one" ESM? If there is a good explanation of this somewhere, please post a link.
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Hello sparky66,
please find the answers to your questions below.
Q: Looking through the documentation, I couldn't find a good explanation of how 2 different ESM's would interact. Everything I have seen only shows tasks within one ESM and one GDS. Is one ESM completely separated from the other?
A: In the current implementation, from the user's point of view, the designations ESM1, ESM2 only serve to assign ESM tasks to a core of the controller. ESM tasks must be assigned to a core by the user so that the ESM tasks can be processed deterministically. In the early days of PLCnext, we implemented central "monitoring" of the ESM tasks. However, this has been decentralized through optimizations, i.e. parts of this monitoring are now performed by each individual ESM task. The one GDS (Global Data Space) enables communication relationships and data exchange between ESM1 and ESM2 tasks and programs that were created in different programming languages.
Q: I cannot have the same task name in both, so there seems to be some overlap. Is it as simple as splitting tasks between them and letting the OS manage timing and priorities so the user can think of it as "one" ESM?
A: According to the current architecture, the names of the tasks must be unique. If the customer has the requirement that the operating system automatically assign certain ESM tasks to a core (and this assignment can be changed depending on the workload during operation), this must be evalueted and formulated as a requirement.
I hope the answers will help you and make this topic clearer.
BR Eduard