OB121 troubleshooting answers
1 question with answers cited from the manufacturer manuals.
- 0S7-1500 CPU in STOP with OB121, Fault_ID 16#3A after partial download, what to check?
An S7-1500 CPU in STOP mode with OB121 and Fault_ID 16#3A indicates a programming error, specifically an attempt to access a data block (DB), function (FC), or function block (FB) that is either not loaded or does not ex…