Siemens SIMATIC S7-1500 warning OB83: Pull/plug interrupt (distributed I/O)
The operating system calls OB83 when a configured, non-disabled distributed I/O module or submodule is removed or inserted (Event_Class 16#39 pulled or not responding, 16#38 plugged). On the S7-1500 the default reaction if OB83 is not configured is to ignore the event. Siemens notes that removing or inserting a central module leads to STOP of the CPU (except some ET 200SP CPUs), and that central S7-1500/ET 200MP modules may only be removed or inserted with the voltage switched off.
Diagnose this with AI
Try Free PLC Fault Diagnostic Upload a keypad photo, the fault history or a parameter export from your Siemens SIMATIC S7-1500. InduQT compares the evidence and suggests the next useful checks.
When it happens
- RUN, when a module in a distributed station is removed, inserted or stops responding
Likely causes and checks
1Module physically removed or replaced in a distributed station
- Points to it
- Maintenance work at the station at the time of the event; Fault_ID 16#51 (IO module removed).
- Check
- Check the module is seated and locked in the station.
2Module not responding (failed, loose or unpowered)
- Points to it
- Event_Class 16#39 without anyone working on the station.
- Check
- Check the module status in Online & diagnostics, its supply and its seating.
3Wrong module inserted
- Points to it
- Plug event followed by a configuration mismatch for that slot.
- Check
- Compare the inserted module’s article number with the configuration.
Telling it apart
- OB83 is one module or submodule; failure of the whole station or IO system calls OB86.
- A central module removed from the S7-1500 rack is not an OB83 event: Siemens states it stops the CPU, and modules must only be changed with power off.
Evidence to collect
- Diagnostics buffer export
- OB83 start information (LADDR, Event_Class, Fault_ID)
- Station and slot of the module; maintenance log
- Article number of the inserted module
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