Allen-Bradley PLC-5 Manual de usuario descargar pdf (Pagina 54)

1785-UM022B-EN-P - February 2002

2-14 Planning to Use Your ControlNet PLC-5 Processor

Understanding Multicast Inputs

This feature enables input devices to send the same data to multiple

processors simultaneously.

Advantages of multicast inputs include:

• Network optimization - reduces network usage since data is sent

only once simultaneously to all connections. This reduction may

allow more complex scheduled connection configurations or

improved unscheduled connection performance.

• Device synchronization - inputting data to all devices

simultaneously improves synchronization between devices

In the following example, the ControlNet PLC-5 processor at node 2

is sending outputs to the adapter at node 3. Nodes 1, 2, and 4 are all

receiving the same input packet from node 3. Nodes 1 and 4 are

considered listen-only and are producing heartbeats to keep their

connections to the adapter alive.

Understanding Multicast Outputs

This feature enables the PLC-5 to simultaneously send the same

output data to more that one target device. To use this feature, both

the PLC-5 and the target devices must support multicast outputs.

Advantages of multicast outputs include:

• Network optimization - reduces network usage since data is sent

only once simultaneously to all connections. This reduction may

allow more complex scheduled connection configurations or

improved unscheduled connection performance.

• Device synchronization - outputting data to all devices

simultaneously improves synchronization between devices

Heartbeat Connection

Point-to-Point Outputs

ControlNet PLC-5

Processor

Node 1

ControlNet PLC-5

Processor

Node 2

ControlNet Adapter

Node 3

ControlNet PLC-5

Processor

Node 4

Multicast Inputs

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Allen-Bradley PLC-5 Manual de usuario Pagina 54