Requested Packet Interval (RPI)

The RPI for I/O connections in a redundant-enabled controller tree is configured the same way as with a simplex controller. The RPI rates of I/O connections impact the loading of the associated
EtherNet/IP™
 communications modules. The RPI can be the same as a non-redundant chassis.

1756-EN4TR Module Considerations

For all communication module catalog numbers beginning with 1756-EN4TR, keep the RPI rate for I/O connections such that the I/O packet rate is under 80% of the maximum (50,000 packets/second).

1756-EN2T Module Considerations

This table describes CPU usage considerations for all communication module catalog numbers beginning with 1756-EN2T.
CPU Utilization Percent
Action
0…80%
No action is required.
Important: This range is the optimal rate.
Greater than 80%
Take steps to reduce your CPU utilization.
  • Adjust the RPI of your connections.
  • Reduce the number of devices that are connected to your module.
  • Add another communication module to the redundant chassis pair (7, max)
IMPORTANT: Your communication module can function at 100% CPU capacity, but at or near this rate, you run the risk of CPU saturation and performance degradation.
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