Are EDS files required to add slave nodes to an EtherNet/IP master?

I am using RSNetworx. I do not have the EDS file for one of my EtherNet/IP nodes. Can I still add the node without an EDS file? If so, how do I do it?

What controller platform are you using?
For any Logix system (ControlLogix, CompactLogix, FlexLogix)EtherNet/IP networking does not require RSNetworx or any .eds files.
Just set up the device's IP settings corresponding to one of the existing subnets' addressing, add the device to the RSL5K Online project tree and physically patch it within the subnet it was addressed for.

If the EtherNet/IP Master is one whose scanlist is configured using RSNetworx, you will need at least a "stub EDS" file that defines the Identity of the device, and preferably also the I/O Assemblies.

While the scanner itself doesn't use EDS files, the RSNetworx software needs to know the basic identity and connection capabilities to create the Scanlist entries.

You can create a basic EDS by hand, just by determining the module identity using RSLinx Classic. The "EZ-EDS" software from ODVA makes it even easier to get the syntax correct.

If you can provide specifics about the Scanner and the Adapter device, Forum users may be able to give more specific advice.