# EtherNet/IP I/O Assembly Data Format Assemblies

When using EtherNet/IP for communicating with Rockwell PLCs, the I/O Assembly data attribute for the input and output data has the following formats:

Input Assembly Instance | Output Assembly Instance
--- | ---
Instance 13 Note: For more information, see EtherNet/IP Input Assembly - Instance 13. | Instance 22 Note: For more information, see EtherNet/IP Output Assembly - Instance 22.

Note: For detailed descriptions of the signals, see Industrial Communications Signals.