Read the corruption pattern
| Every byte wrong | Large baud mismatch, inversion or wrong electrical interface. |
|---|---|
| Some ASCII recognizable | Close baud rate, wrong framing or clock drift. |
| Errors at long runs/high load | Clock tolerance, buffering, noise or signal integrity. |
| Parity errors only | Parity mode/data-bit configuration mismatch. |
Evidence sequence
- Verify RS232 voltage levels and signal ground.
- Measure bit timing or decode a passive waveform.
- Test full framing combinations offline against repeated known patterns.
- Compare both directions; endpoints may be configured differently.
- Inspect cable length, grounding/noise only after logical settings are proven.
Use baud detection, traffic capture, pinout diagnosis and the pillar.
Provide raw waveform/capture, port settings, error counters and cable/environment details.