Rockwell Automation has provided a tool called EtherNet/IP Capacity Tool that is designed to help you calculate the resources required to support a control network. The tool takes a conservative approach to estimate the requirements of your network usage based on a few data points you provide it.
EtherNet/IP Capacity Tool is used to measure the networking capacity of a single scanner processor. A scanner processor is either an EtherNet/IP module, such as the ControlLogix ENBT, or a Logix controller with a built-in EtherNet/IP port, such as the CompactLogix L32E. If a scanner processor is at maximum capacity, in most cases, an additional EtherNet/IP module or controller can be added to the control solution. A separate EtherNet/IP Capacity Tool report can be created for each scanner processor network.
When you calculate your capacity, the tool provides you with the available CIP connections, TCP connections, I/O Packets Per...