# lochinvar-native-modbus: mapping Knight boiler telemetry

> lochinvar-native-modbus reconstructs the read-only Modbus register map exposed by Lochinvar Knight boilers through the SMART SYSTEM display's USB PC Connection port. Probe scripts and display comparisons identify telemetry for temperatures, firing rate, flame signal and counters; ESPHome and MQTT bridges publish readings to Home Assistant.

- Type: Case study
- Targets: Protocol
- Category: Independent reconstruction cases
- Relationship: Independent reconstruction project
- Sources reviewed: 2026-11-06
- Added to the catalog: 2026-11-08
- Original resource: <https://github.com/KB1RMA/lochinvar-native-modbus>
- Primary source: <https://github.com/KB1RMA/lochinvar-native-modbus/blob/55c207ac1bcb32a0d0b117e3967266a82f621404/docs/reverse-engineering-log.md>
- Catalog page: <https://awesomerea.org/resources/lochinvar-native-modbus-case/>
- Record JSON: <https://awesomerea.org/resources/lochinvar-native-modbus-case/record.json>
- Chinese version: [简体中文](https://awesomerea.org/zh/resources/lochinvar-native-modbus-case/index.md)

## Requirements & limits

- **Prerequisites:** A boiler with the SMART SYSTEM display and USB PC Connection port, a USB cable, and an ESP32-S3 board or Linux Docker host.
- **Prerequisites:** Home Assistant is required; the MQTT route also needs a broker.
- **Limits:** Only read requests are implemented; lockout codes are not mapped, and some values remain guesses.
- **License:** No licence file in the repository.

## Primary sources

1. <https://github.com/KB1RMA/lochinvar-native-modbus/blob/55c207ac1bcb32a0d0b117e3967266a82f621404/docs/reverse-engineering-log.md>
2. <https://github.com/KB1RMA/lochinvar-native-modbus/blob/55c207ac1bcb32a0d0b117e3967266a82f621404/README.md>

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## About this entry

The description was reviewed against primary sources.
Original editorial content: MIT. Linked projects, papers and assets retain their own rights and licenses.