---
title: "Start cable encoder calibration process"
method: POST
path: "/api/v1/reel/calibration/start"
tags: ["v1", "cable-calibration"]
---

# Start cable encoder calibration process

`POST /api/v1/reel/calibration/start`

Initiate cable encoder calibration by recording the current encoder position as baseline.

The encoder position is recorded as the starting reference point for calibration calculations. Once started, use reel controls to unwind a measured distance of cable (1-10 meters), then complete the process with the finish endpoint.

Emergency stop remains functional during calibration. Monitor calibration status via the `is_cable_counter_calibrating` field in heartbeat responses.

## Response `200`

Calibration initiation status with system state information

- StartCalibrationResponse — Response for starting cable encoder calibration process. Initiates calibration mode and prepares system for manual measurement. Monitor status via heartbeat `is_cable_counter_calibrating` field.
  - `action` string, required — The action that was requested or performed by the endpoint
  - `error` boolean, required — Indicates whether the operation encountered an error
  - `error_msgs` string[] — List of error messages if the operation failed
  - `result` CalibrationResult, required — Result data for calibration start and cancel operations.
    - `calibrating` boolean, required — Current calibration status of the cable encoder system. Indicates whether the system is actively in calibration mode. Monitor this status via heartbeat `is_cable_counter_calibrating` field. Emergency stop remains functional during calibration.

## Other responses

- `401` — Could not validate credentials
- `403` — Setup required before using this endpoint
- `500` — Internal server error

---

[API](https://skmtc.net/reach-systems-tech/apis/reelapi-v1.md) · [All operations](https://skmtc.net/reach-systems-tech/apis/reelapi-v1/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/reach-systems-tech/reelapi-v1/versions/1dd366a9c6a3/schema)