node-red-contrib-frequency-meter

A simple NR node that measures the frequency of messages flowing through a graph. Just attach its INPUT to a flow and you'll be getting frequency of messages in Hz on its OUTPUT connector, formatted as:

msg: {topic: "frequency", payload: "3.4"}

You'll also get a nice status indication with the measured frequency (in Hz, rounded to 3 decimals) directly in the NodeRed interface, but you'll have to enable the display of node statuses first.

Just beware that these frequency messages are generated at preset intervals and their generation is not necessarily triggered by arriving messages.

Therefore:

You must not wire this node inline with your flows, as its not going to convey the incoming message to the output connector. Keep it as a peripheral - terminal node instead.

The measured frequency is also kept in NodeRed's global context eg for use with function blocks. You can access its current value with: context.global.frequencies[<node name>] so don't forget to give your nodes some unique names! If you're going to use it from within another node, use: RED.settings.functionGlobalContext.frequencies[<node name>]

Disclaimer: Do not use this software to control nuclear reactors! (and ice-cream makers too!)

Here's a demo flow: [{"id":"abe0d1c5.541f3","type":"frequency","name":"freq1","interval":"10000","ntfyinterval":"500","x":403,"y":258,"z":"4574009.fba8c","wires":[[]]},{"id":"1b71fdec.e48e02","type":"inject","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"x":170,"y":200,"z":"4574009.fba8c","wires":[["abe0d1c5.541f3"]]}]

This node is based on https://github.com/pgte/frequency-meter - Huge respect to Pedro Teixeira.