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57 lines
2.1 KiB
Markdown
57 lines
2.1 KiB
Markdown
node-red-node-rbe
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=================
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A <a href="http://nodered.org" target="_new">Node-RED</a> node that
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provides report-by-exception (RBE) and deadband capability.
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The node blocks unless the incoming value changes - RBE mode, or
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changes by more than a certain amount (absolute value or percentage) - bandgap modes.
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Install
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-------
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Run the following command in your Node-RED user directory - typically `~/.node-red`
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npm i node-red-node-rbe
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Usage
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-----
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A simple node to provide report by exception (RBE) and bandgap functions
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- only passes on data if it has changed.
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This works on a per `msg.topic` basis. This means that a single rbe node can
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handle multiple topics at the same time.
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### RBE mode
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The node doesn't send any output until the `msg.payload` is different to the previous one.
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Works on numbers and strings. Useful for filtering out repeated messages of the
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same value. Saves bandwidth, etc...
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### Deadband and Narrowband modes
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In deadband modes the incoming payload should contain a parseable *number* and is
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output only if greater than + or - the *band gap* away from the previous output.
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The narrowband modes will block if the incoming value change is greater than + or - the band gap
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away from the previous value. Useful for ignoring outliers from a faulty sensor for example.
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You can specify compare with *previous valid output value* or *previous input value*.
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The former ignores any values outside the valid range, whereas the latter allows
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two "bad" readings in a row to reset the range based on those values.
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For example a valid step change.
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The deadband value can be specified as a fixed number, or a percentage. E.g. 10
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or 5% . If % mode is used then the output will only get sent if the input payload
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value is equal or more than the specified % away from the previously sent value.
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For example - if last sent value was 100, and deadband is set to 10% - a value
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of 110 will pass - then the next value has to be 121 in order to pass (= 110 + 10% = 121).
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This is mainly useful if you want to operate across multiple topics at the same
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time that may have widely differing input ranges.
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Will only accept numbers, or parseable strings like "18.4 C" or "$500"
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