Rockwell Automation 1738-AENTR, Series B POINT I/O and ArmorPOINT I/O Dual Port EtherNet/IP Adapters User Manual - Manual (Page 80)

72 Rockwell Automation Publication 1734-UM017B-EN-P - October 2013
Chapter 5 Configure the Adapter for Direct Connection and Rack Optimization in RSLogix 5000 Software
6. Click Set Chassis Size in Module.
7. Read and acknowledge the warning dialog.
8. Click OK to continue.
9. Notice the chassis size in the module is modified to 5.