Return values, communication failures, and alarm detection

This page is a static source audit of source_reference/dobot_core/dobot_ctrl.py, dobot_tcp.py, and dobot_error.py; it is not hardware validation.

Return-value contracts

API	Normal result	Failure or limitation
`get_digital_input(index)`	`True` for HIGH, `False` for LOW	Non-success Dashboard replies, parse errors, missing values, and exceptions also return `False`; LOW cannot be distinguished from failure by return value alone.
`get_IO(id_num)`	`1` or `0` from the `digital_outputs` Feedback bitfield	`id_num < 1` raises `ValueError`. Missing initial Feedback raises `RuntimeError`. Feedback freshness is not verified after the initial frame.
`set_IO(id_num, value)`	`True` for Dashboard `DO` return code 0	`False` otherwise; no physical-output readback verification.
`reset_error()`	`True` for successful `ClearError` response	`False` for unsuccessful response; does not establish that the underlying fault was resolved.
`get_motion_complete()`	`True` when `busy_status` is false	`busy_status` checks `RunningStatus` and `JogStatus`. Initial Feedback timeout can raise `RuntimeError`. `True` does not prove target reached or alarm-free completion.
`wait_for_complete()`	`True` after successful `Sync()` and no detected alarm	`False` for failed Sync or detected alarm. Not all communication/alarm-query failures are detectable. The public `DobotCtrl` method has no arguments.
`get_error()`	List of alarm IDs	Missing Dashboard, failed `GetErrorID`, or malformed/empty payload can produce `[]`.
`get_error_code()` / `get_error_count()`	First ID / count	The above failures can also produce `0`.
`check_error()`	`get_error_count() == 0`	Can return `True` if alarm retrieval fails; not a connection-health check.

Feedback and alarm-query boundary

_state() waits for the first valid Feedback frame and raises RuntimeError on timeout. It does not validate age of cached Feedback after the first frame. motion_error_active() catches RuntimeError from _state_getter("ErrorStatus", timeout=0.1) and treats the error status as false. When GetErrorID() also yields an empty alarm list because retrieval failed, the control flow can report no active alarm without having established that status.

Operational implication: Do not use an isolated False, 0, [], or True as proof of connection health or motion safety. This page documents existing behavior; it does not change the implementation.

Scope

Only the provided Python source branches and return paths were inspected. Hardware alarms, network interruptions, I/O wiring, TCP timeouts, and Sphinx HTML output were not tested.