Two different M580 CPUs exist:
Depending on the level performance requested by the process, the BMECXM module can be scanned by the RIO or the DIO scanner of the M580 CPU. Both scanners use EtherNet/IP to scan the module.
In the same M580 PAC, several BMECXM modules can be connected to the same or different I/O scanner.
For detail on EtherNet/IP connection behavior when the module switched to
FALLBACK state, refer to chapter
Fallback Strategy.
When the BMECXM is scanned by the RIO scanner, the main capabilities are:
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Higher performance constraints
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Highest performance expectation (bandwidth sharing and controlled cycle timing on CANopen and EtherNet/IP).
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Bandwidth controlled (RSTP)
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Timing and cycle synchronized (with either MAST task or FAST task.)
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Support up to 24 kb of IO data.
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RPI is automatically calculated by Control Expert
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Motion function blocs (MFB) are supported
When the BMECXM is scanned by the DIO scanner, the main capabilities are:
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Lower performance constraints
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Lowest performance expectation, no constraint (no bandwidth sharing and no controlled cycle).
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No control and no synchronization.
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Can only support up to 8 kb of IO data.
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No support of motion function blocs (MFB)
Whatever the BMECXM is scanned by RIO or DIO scanner, all the variables belonging to the same slave are kept consistent, meaning exchanged in the same EtherNet/IP assembly (one for input, one for outputs).
The same EtherNet/IP assembly can contain the data of several devices, and even the data of all the devices (the complete process image).
NOTE: When the BMECXM is scanned by the RIO scanner, all the BMECXM process image is refreshed in the PLC scan. This service is interesting only if the process image has been refreshed on the CANopen fieldbus side during the same period.
