node-red-contrib-data-view

Node-RED node to preview data with a simple line chart inside the Node-RED flow editor. This node was inspired by the simple image preview node node-red-contrib-image-output.

The node expects the input msg.payload or other specified property of the input message to contain a number value. The node will then generate a line chart in the flow editor under the node displaying values received over time.

NOTE: This node is a work in progress. The intended use case for this node is for simple demos and debugging. The state of the chart is currently maintained in the client, so that refreshing the page, or opening a new view on the flow will cause the chart to reset. I expect to add additional chart options, chart types and support different shapes of data. Feedback is welcome.

Installation

Either use the Editor - Menu - Manage Palette - Install option, or run the following npm command in your Node-RED user directory (typically ~/.node-red):

npm i node-red-contrib-data-view

Node usage

This node can be used to view simple line charts inside the Node-RED flow editor as illustrated below.

The following example demonstrates how to inject numbers into the node to generate charts. To clear a chart, send a null or undefined msg.payload value as shown, or click on the trash button in the top right corner.

[{"id":"2cd7059b.70ec6a","type":"data-view","z":"de60a83e.dce718","name":"wide chart","width":"400","height":"160","points":"100","active":true,"passthru":false,"outputs":0,"x":550,"y":120,"wires":[]},{"id":"1459af05.cfcc01","type":"inject","z":"de60a83e.dce718","name":"trigger data","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":true,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":150,"y":120,"wires":[["93544758.228ec8"]]},{"id":"93544758.228ec8","type":"function","z":"de60a83e.dce718","name":"generate values","func":"msg.payload = Math.floor(Math.random() * 100)-50;\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","x":360,"y":120,"wires":[["2cd7059b.70ec6a","e2c1381f.9dad28","47a657d1.c696f8"]]},{"id":"8841bc1f.0fee1","type":"debug","z":"de60a83e.dce718","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":730,"y":340,"wires":[]},{"id":"a0e15f78.4871c","type":"inject","z":"de60a83e.dce718","name":"clear chart","props":[{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"test","x":160,"y":160,"wires":[["2cd7059b.70ec6a"]]},{"id":"4de026cb.33c388","type":"inject","z":"de60a83e.dce718","name":"send bad data","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"strings can't be graphes","payloadType":"str","x":150,"y":200,"wires":[["2cd7059b.70ec6a"]]},{"id":"e2c1381f.9dad28","type":"data-view","z":"de60a83e.dce718","name":"pass through","width":"300","height":"160","points":"50","active":true,"passthru":true,"outputs":1,"x":550,"y":340,"wires":[["8841bc1f.0fee1"]]},{"id":"47a657d1.c696f8","type":"data-view","z":"de60a83e.dce718","name":"","width":200,"height":160,"active":true,"passthru":false,"outputs":0,"x":320,"y":340,"wires":[]}]

This example flow is also available via the 'Import' menu in the Node-RED flow editor.

Node configuration

Property

Choose the message property containing the value to plot, msg.payload by default.

Height

The height (in pixels) of the chart.

Width

The width (in pixels) of the chart.

Line points

The number of points to display in the chart before they are dropped. The client side code maintains a circular buffer for each node.

Hide chart on deactivate

Hide the chart when node is deactivated to reduce clutter. This is set to true to default. Note that when the node is deactivated, any data sent to the chart is dropped.

Allow data passthrough

When selected this adds an output wire to the node in order to pass the original message through to a following node. This performs better than forking the wires, however it does remove the enable/disable button.