The PLCs have an integrated preemptive real-time operating system that supports 100 priorities from 0 (lowest priority) to 99 (highest priority). Hereof 0 ... 49 in the non-real-time area and 50 ... 99 in the real-time area.
For real-time tasks in the IEC user program 16 priorities 0 (highest priority) ... 15 (lowest priority) can be used. They correspond to the operating system priorities 67 (for IEC task priority 0) ... 52 (for IEC task priority 15).
The file system, the memory card and flash tasks run on lowest real-time priority 50.
The non-real-time IEC task priority 16 runs in the non-real-time area. Likewise, all Ethernet protocols and the diagnosis system run in the non-real-time area.
As of Automation Builder 2.4.1 and “SystemFW” 3.4.1 provides a new PLC boot parameter Communication Schema (non-real time vs. real-time Ethernet data):
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Name: “Default”
Description: Balanced priority for communication via communication modules (CMs) and onboard Ethernet communication.
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Name: “Communication modules”
Description: Priority and high performance for communication module (CM) based communication via sync tasks. Lower priority for onboard Ethernet and I/O bus.
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Name: “Onboard Ethernet”
Description: Priority for onboard Ethernet communication (e. g. via Modbus TCP). Lower priority for communication via communication modules (CMs)
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Name: “Realtime onboard Ethernet”
Description: Very high priority for onboard Ethernet communication (e. g. EtherCAT, PROFINET, Ethernet/IP). Low priority for communication via communication modules (CMs)
The value “Realtime onboard Ethernet” is reserved for later use and has currently the same settings as “Onboard Ethernet” and in addition the I/O bus on the same priority as the Ethernet.
In version of “SystemFW” 3.5.0 the priority of onboard CAN interface has been adapted and is now included in the priority schemas.
In addition the parameter Communication Schema is now also available for the eCo PLCs.