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name: modbus-troubleshooting description: Diagnostics for Modbus in Home Assistant custom components—framing/extra-data errors, unit_id mismatches, pacing/timeouts, write contention, and logging patterns. license: Complete terms in LICENSE.txt

Modbus Troubleshooting

Use when Modbus IO misbehaves (timeouts, extra data, wrong values).

Quick checks

• Verify device_id/unit_id on every call; wrong unit → timeouts.
• Add pacing (message_wait_milliseconds) and avoid immediate post-write polls.
• For RTU-over-TCP, flush/reset framer/buffer; reconnect on extra-data.
• Log address/unit/function and raw words to spot endian or offset issues.

References

• references/common-failures.md
• references/logging-and-dumps.md
• references/mitigations.md