Rockwell Automation 1738-AENTR, Series A 1734 POINT I/O and 1738 ArmorPOINT I/O 2 Port Ethernet/IP Adapter User Manual - Manual (Page 63)

Rockwell Automation Publication 1734-UM014B-EN-P - June 2013 55
Configure the Adapter for Direct Connection and Rack Optimization in RSLogix 5000 Software Chapter 5
The New Module properties dialog opens.
9. Verify that the requested packet interval (RPI) is appropriate for your
system. You use this value for the rack-optimized connection to the I/O
modules.
10. Click OK. The name of the adapter appears in the I/O tree.
IMPORTANT To avoid overloading the adapter, we recommend that you set RPI no
less than 10 ms for rack connections and 50 ms for direct connections.