In this topology, the BMENOS0300 network option switch is added to the main rack. This makes it possible to add a second DIO ring (in addition to the DIO ring connected to the CPU), and thereby extend the number of distributed equipment devices beyond the 40 devices supported by a single DIO ring. The ports of the BMENOS0300 module are used as follows:
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The two network ports are configured for a DIO Ring.
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The service port is configured as an Access port, and supports an engineering tool (for example, Control Expert) resident on a PC.
NOTE: Instead of a PC, a DIO cloud could be connected to the service port.
1
Standalone PAC on local rack
2
Ethernet DIO ring
3
Distributed equipment
4
Ethernet non-looping daisy chain
5
Engineering tool resident on PC
NOTE:
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To achieve acceptable recovery times, limit each DIO design to a single DIO main ring without sub-rings.
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RSTP limits the size of the DIO ring to a maximum of 40 switched devices, including the BMENOS0300 module.
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When you set the BMENOS0300 network rotary switch to
DIO Ring, configure a distributed equipment Ethernet device to be the RSTP root bridge. Refer to the topic
Device Rotary Switch Positions for information about the effects of selecting
DIO Ring.
