MQTT Configuration

Send tasks to thermal printers via MQTT protocol for remote and networked printing.

Connection Settings

Broker URL

Define the MQTT broker address (mqtt:// or mqtts://)

Topic

Set the topic where print jobs are published

QoS (Quality of Service)

Choose the delivery guarantee level for messages

Retain

Keep the last message on the broker (usually disabled for printing)

Authentication (optional)

Provide username and password if your broker requires it

JSON Template

Customize the JSON message format sent to the MQTT broker.

Available Variables:

${image_base64}: Base64-encoded PNG image of the task
${paper_width_mm}: Paper width in millimeters
${paper_height_mm}: Paper height in millimeters
${timestamp}: Current timestamp in milliseconds

Default JSON Template:

{
  "data_type": "png",
  "data_base64": "${image_base64}",
  "paper_type": 0,
  "paper_width_mm": ${paper_width_mm},
  "paper_height_mm": ${paper_height_mm},
  "cut_paper": 1
}

You can customize this template to match your MQTT printer bridge’s expected format.

Image Settings

MQTT always uses image mode for maximum compatibility across different printer types.

DPI (Dots Per Inch)

Set print quality

Width

Set paper width in millimeters to match your printer

Padding (in millimeters)

Set margins (left, right, top, bottom); account for printer hardware margins

Font Sizes (in pixels)

Adjust text sizes for breadcrumb, title, and checklist

Live Preview

See a real-time preview of how your task will look when printed