0x16 (0x16) — Object does not exist

The specified object class is not implemented on this device at all.

Start free EtherNet/IP → canonical

Diagnosis

When you hit this

Querying an object class the device does not support, such as asking a simple sensor for a Motion object.
Assuming an optional CIP object is present because a similar device has it.

Resolution

How to fix it

Read the Identity object first
Class 0x01 is mandatory on every CIP device and tells you vendor, product code, and revision — enough to look up what else exists.
Consult the EDS file
The device's EDS enumerates supported classes. It is the authoritative answer to whether an object exists.

Normalization

What Forge does about it

This is a configuration or addressing mistake on the wire, upstream of anything Forge sees. Where Forge helps is the step after you fix it: once the point returns data, its vendor tag name maps to a canonical field automatically, so you do not also have to hand-maintain a name table for every point you just re-addressed.