S7 0x05 (0x05) — Address out of range

The requested DB, byte, or bit lies outside what the CPU has allocated. The connection is healthy; the address is not.

Start free PROFINET / S7 → canonical

Diagnosis

When you hit this

Reading past the end of a data block, often after the block was shortened and the client was not updated.
Addressing a DB number that does not exist in the current program.
Reading an optimized-access DB, whose contents have no fixed byte addresses at all.

Resolution

How to fix it

Turn off optimized block access
In TIA Portal, a DB with optimized access cannot be read by absolute address. Uncheck it, or use symbolic access instead.
Re-read the block length
After a program change the DB may be shorter. Query the block list rather than assuming last known size.
Check the DB number, not just the offset
A missing DB and a bad offset return the same code.

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.