Jiggadoo

Ethernet/IP bus line topology to ring.

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I have an Ethernet/IP bus and system including Ethernet/IP devices with CPU 1756-L81ES ControlLogix. PLC is connected to the switch. Bus is built from the switch as a line. Can I connect the last device on the bus back to switch again? In thes case bus will be ring. Do I get problems with connection it this way. Switch is Stratix 2500, which is lightly managed switch. I believe it will increase the traffic in the bus.

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That model does not appear to support DLR (Device Level Ring).  So no, do not connect the final leg back into the switch.

If you need the redundancy features of DLR, you will need a Stratix 5400 series switch, or one of the Stratix 5700 series switches (certain models).  This document has the various models features:

https://literature.rockwellautomation.com/idc/groups/literature/documents/qr/enet-qr001_-en-e.pdf

Edited by pturmel
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Thanks, we are not using DLR.

Should I assume that it will make bus unstable if there is traffic both directions, without DLR. 

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15 minutes ago, Jiggadoo said:

it will make bus unstable

It can.  In this case the 2500's spanning tree protocol might catch it.  If nothing catches the multipath condition, you will have broadcast storms that crush your bandwidth.

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