MQTT GeneralInstall

Summary

Publish a message to an MQTT topic to wait for a specific image match on a browser page using image-based automation; optionally wait for and return a response message from a specified MQTT response topic.

Inputs

• Topic (required) — MQTT topic used for publishing the wait_to_image command to trigger image matching automation.
• QoS — Quality of Service level for the MQTT publish (0, 1, or 2).
• Include Input Items — Whether to include selected fields from the input items in the MQTT payload under inputItems.
• Include Input Items Fields — Comma or newline-separated list of fields from input items to include in the payload if Include Input Items is true.
• Wait For Response — If true, the node subscribes to a response topic and waits for a reply before completing.
• Response Topic (required) — MQTT topic to subscribe for the awaited response message when Wait For Response is enabled; defaults to RES_.
• Response Timeout (ms) — Milliseconds to wait for a response message before timing out. Defaults to 10000.
• Parse Response As JSON — Whether to parse the response message payload as JSON if possible.
• Image Input (required) — Local file path or URL of the sample image to use for matching against the page screenshot.
• Timeout (sec) — Total number of seconds to wait for the image match to occur before timing out. Defaults to 30.
• Interval (sec) — Number of seconds to wait between retry attempts to locate the image. Defaults to 1.
• Confidence — Confidence threshold (0.01 to 1.0) required for image matching to be considered successful. Defaults to 0.9.
• Workflow — Name of the workflow isolated for temporary cache when matching images. Defaults to 'workflow'.
• Full Page — If true, capture and search the entire page for the image; if false, search only the viewport. Defaults to false.
• Max Results — Maximum number of matching results to return. Defaults to 20.

Output shape

a list of items reflecting the original input items augmented with details about the MQTT publish action, including action keys, payload inputs, and optionally, response data if Wait For Response is enabled.

If 'Wait For Response' is true, the node subscribes to the specified 'Response Topic' and waits up to 'Response Timeout (ms)' for a message. The response payload is parsed as JSON if 'Parse Response As JSON' is true. The output items include an 'mqtt' field with topic, action details, payload, and possibly a response field containing topic, raw response, and parsed payload. If no input items are received, one output item with the MQTT details is returned. Errors trigger node failure unless 'Continue On Fail' is set.

Examples

Example 1: Publish a wait_to_image command on the topic 'playwright/image/check' with specified image, waiting up to 20 seconds for the image to appear on the page.

Set 'Topic' to 'playwright/image/check', 'Image Input' to local path or URL to the sample image, 'Timeout (sec)' to 20, and 'Wait For Response' to false. The node publishes the message and completes immediately.

Example 2: Publish the wait_to_image command and wait for a response indicating success.

Enable 'Wait For Response', configure 'Response Topic' (e.g., RES_playwright/image/check), and increase 'Response Timeout (ms)' as needed. The node waits for a matching reply on the response topic before outputting the response data.

Links

• n8n community nodes installation guide