Rockwell-automation Ethernet Design Considerations Reference Manual Manual de usuario descargar pdf (Pagina 46)

46 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013

Chapter 3 Ethernet Infrastructure Features

QoS Guidelines

Follow these guidelines with QoS:

• Manage the output queues based on application needs. Schedule precision

and motion control packets in the highest priority queue.

• QoS gives preferential treatment to Industrial Automation and Control

System Network traffic at the expense of other network traffic.

• QoS is integrated into the Stratix 8000 and Stratix 8300 switch

configurations.

• Deploy QoS consistently throughout Industrial Automation and Control

System Network.

Resiliency

A resiliency protocol maintains parallel links for redundancy while avoiding

loops. Network convergence time is a measure of how long it takes to detect a

fault, find an alternate path, and recover from the fault:

• During the network convergence time, some portion of the traffic is

dropped by the network because interconnectivity does not exist.

• Communication drops if the convergence time is longer than the Logix

connection timeout.

Time Calculations in a Logix5000 System

Network convergence must occur before the control system is impacted:

• Logix message instruction (MSG) time out (explicit, CIP Class 3)

• I/O connection timeout (implicit, CIP Class 1), 4 x RPI, 100 ms

minimum

• Logix Producer/Consumer connection timeout (implicit, CIP Class 1),

4 x RPI, 100 ms minimum

• Safety I/O connection timeout (implicit, CIP Class 1), 4 x RPI (default)

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Rockwell-automation Ethernet Design Considerations Reference Manual Manual de usuario Pagina 46