Charts - kamilfb/mqtt-spy GitHub Wiki

• Auto-refresh for live data
• Historical values
• One or more topics (select which from the summary table or define new series)
• Plotted value can be:
  • Message payload (could be formatted)
  • Result of a JSONPath expression (for JSON messages)
  • Result of an XPath expression (for XML messages)
  • Message payload size
• Message load charts (i.e. how many messages are being received)
• Pan and zoom
• Value tooltips
• Manual and automatic export of the chart image to a PNG file

To plot a result of a JSONPath expression do the following:

• Add a new series (click the Add button) or edit an existing one (select Edit in the context menu of the existing series)
• Change the type of the series to JSONPath
• Type in your JSONPath expression into the 'Value expression' field

For the following JSON document:

{
          "humidity": 59.6,
          "temp": 19.7
}

the following expression will extract the humidity value:

$.humidity

To plot a result of a XPath expression do the following:

• Add a new series (click the Add button) or edit an existing one (select Edit in the context menu of the existing series)
• Change the type of the series to XPath
• Type in your XPath expression into the 'Value expression' field

For the following XML document:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<msg>
          <temp>20.9</temp>
          <energy>108</energy>
</msg>

the following expression will extract the energy value:

/msg/energy

To pan around the chart, use right click drag or CTRL/CMD + left click.

For zooming, use the following:

• Drag mouse (with left click) in plot area to zoom in both axes
• Drag mouse (with left click) on X axis to zoom in that axis only
• Drag mouse (with left click) on Y axis to zoom in that axis only
• Mouse wheel to zoom in/out plot area (X axis and Y axis)
• Mouse wheel on X axis to zoom in/out that axis only
• Mouse wheel on Y axis to zoom in/out that axis only

To reset, double click on the chart or use the context menu in Options.