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Chapter 1
About the Dynamix 1444 Series Dynamic Measurement Module
Network Connectivity and
Considerations
20
Within the system, the DYN module uses an RS-485 proprietary local bus for
communication with its expansion modules. The DYN module interfaces to
the EtherNet/IP network as an adapter device using single-node addressing.
Given the presence of two Ethernet RJ45 ports and integrated network switch,
the system can be used in different network topologies:
• Linear
• Star
• DLR
Given an available internal switch, a linear module-to-module Ethernet
connection can be established without the need for a local Ethernet router/
switch. A linear topology is not the preferred solution since any module or
cable failure results in loss of communication to that part of the network,
downstream of the fault.
The star topology uses a multi-port Ethernet router/switch to establish point-
to-point connections to DYN modules in the network. This topology
increases network reliability, although it doesn't offer point-to-point
connection redundancy.
IMPORTANT The Dynamix 1444 Series is essentially a one-port device with a 2-port
switch. Normal star topology redundancy that uses the Spanning Tree
Protocol (STP – IEEE 802.1D or its newer and faster recovery variant RSTP –
IEEE 802.1w) does not work for this EtherNet/IP application.
Most preferred from the perspective of performance, support, and ease of
installation is the use of the Device Level Ring (DLR) redundancy method.
The DLR redundancy mode lets you make a simple ring-based module-to-
module connection to achieve a network with excellent reliability and fast
recovery in the presence of one failure. This topology is recommended for
machine protection applications.
Under control of one of the ring devices that are configured to act as ring
supervisor, a network disruption (cable or module) can be detected. This
disruption causes communication flow direction that is reversed in a few 100
ms to become a star connection of two linear connections.
IMPORTANT The Dynamix DYN module cannot provide the required Ring Supervisor
capability; therefore, an EtherNet/IP controller interface with DLR
functionality is required (direct interface to Controller system). However, for
downstream networks, a separate 1783-ETAP (3-port EtherNet/IP tap) can
be used to act as Ring Supervisor for multiple EtherNet/IP adapters and
provide connection to the higher-level EtherNet/IP network.
Multiple rings are either part of a further ring topology or connected with a
star topology. In the latter case, the trunking method can be used where
multiple parallel cables can be connected between switches such to increase
bandwidth. For supported products, the redundancy level is increased.
Rockwell Automation Publication 1444-UM001D-EN-P - June 2018
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