Handle messages at a regular rate
Problem
You want to handle messages at a regular rate, ignoring messages that arrive too quickly. For example, you have a sensor sending data every second but you only want to handle an update every 5 seconds. The messages you handle must be the most recent.
Solution
Use a Delay node configured to rate limit the messages
passing through it with the option to drop intermediate messages enabled.
Example
[{"id":"8a1bcd7d.f6b67","type":"inject","z":"ac14500e.2c57d","name":"Inject Array","topic":"","payload":"[0,1,2,3,4,5,6,7,8,9]","payloadType":"json","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":110,"y":1380,"wires":[["bd4bdd42.bd1b"]]},{"id":"bd4bdd42.bd1b","type":"delay","z":"ac14500e.2c57d","name":"","pauseType":"rate","timeout":"5","timeoutUnits":"seconds","rate":"1","nbRateUnits":"5","rateUnits":"second","randomFirst":"1","randomLast":"5","randomUnits":"seconds","drop":true,"x":320,"y":1380,"wires":[["be20c513.237c78"]]},{"id":"be20c513.237c78","type":"debug","z":"ac14500e.2c57d","name":"Debug","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":510,"y":1380,"wires":[]}]
Discussion
The rate limiting mode of the Delay node can be used to
change the rate of messages passing through it. With the option to drop intermediate
messages enabled, it will discard any message that arrives within the rate limit
interval.
