# One node inputs output only if inputs are different

**URL:** <https://discourse.nodered.org/t/one-node-inputs-output-only-if-inputs-are-different/67628>\
**Category:** General\
**Created:** [12 September 2022 22:18 UTC](https://discourse.nodered.org/t/one-node-inputs-output-only-if-inputs-are-different/67628 "2022-09-12T22:18:11Z")\
**Posts on this page:** 12\
**Page:** 1

<div class="post-metadata">

**Author:** ![hugovsky](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/hugovsky/32/67691_2.png) [@hugovsky](https://discourse.nodered.org/u/hugovsky)\
**Post date:** [12 September 2022 22:18 UTC](https://discourse.nodered.org/t/one-node-inputs-output-only-if-inputs-are-different/67628/1 "2022-09-12T22:18:11Z")

</div>

Hi all. I've searched and couldn't find a solution to my problem. I think it should be easy but can't figure it out on my own. Just starting with node-red. I'm using it with home assistant.

I have a poll state node that checks temp every 10 minutes. I use this flow to send a message to my tv. What I want is to be able to only send the message if the temperature changes. Better yet, would be output if change and compare for 3 times and if even then temperature didn't change output anyway.

Can you help me?

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<div class="post-metadata">

**Author:** ![jbudd](https://avatars.discourse-cdn.com/v4/letter/j/5f8ce5/32.png) [@jbudd](https://discourse.nodered.org/u/jbudd)\
**Post date:** [12 September 2022 22:20 UTC](https://discourse.nodered.org/t/one-node-inputs-output-only-if-inputs-are-different/67628/2 "2022-09-12T22:20:55Z")

</div>

Have you looked at the Filter node?

It ofers "block unless the value changes" and "block unless the value changes by n%"

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<div class="post-metadata">

**Author:** ![E1cid](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/e1cid/32/77971_2.png) [@E1cid](https://discourse.nodered.org/u/E1cid)\
**Post date:** [12 September 2022 22:37 UTC](https://discourse.nodered.org/t/one-node-inputs-output-only-if-inputs-are-different/67628/3 "2022-09-12T22:37:06Z")

</div>

This should work

```auto
[{"id":"89faddb4.adcff","type":"inject","z":"aaa27ee4852b402b","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"20","payloadType":"num","x":110,"y":660,"wires":[["69d74780.c3706","d8105e11.a53ba8"]]},{"id":"69d74780.c3706","type":"rbe","z":"aaa27ee4852b402b","name":"","func":"rbe","gap":"","start":"","inout":"out","septopics":true,"property":"payload","x":330,"y":660,"wires":[["e5efcba5.436668"]]},{"id":"d8105e11.a53ba8","type":"join","z":"aaa27ee4852b402b","name":"","mode":"custom","build":"array","property":"payload","propertyType":"msg","key":"topic","joiner":"\\n","joinerType":"str","accumulate":false,"timeout":"","count":"3","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"","reduceFixup":"","x":330,"y":720,"wires":[["b91de405.26f66"]]},{"id":"defae9a4.8f94a","type":"inject","z":"aaa27ee4852b402b","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"21","payloadType":"num","x":110,"y":720,"wires":[["69d74780.c3706","d8105e11.a53ba8"]]},{"id":"e5efcba5.436668","type":"change","z":"aaa27ee4852b402b","name":"","rules":[{"t":"set","p":"complete","pt":"msg","to":"true","tot":"bool"}],"action":"","property":"","from":"","to":"","reg":false,"x":510,"y":660,"wires":[["d8105e11.a53ba8"]]},{"id":"b91de405.26f66","type":"change","z":"aaa27ee4852b402b","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"$$.payload[-1]","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":520,"y":720,"wires":[["f5f3d227.61fc28"]]},{"id":"f5f3d227.61fc28","type":"debug","z":"aaa27ee4852b402b","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":730,"y":720,"wires":[]}]

```

if 3 payloads the same it will output, or if payload changes it will output.

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<div class="post-metadata">

**Author:** ![hugovsky](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/hugovsky/32/67691_2.png) [@hugovsky](https://discourse.nodered.org/u/hugovsky)\
**Post date:** [12 September 2022 22:37 UTC](https://discourse.nodered.org/t/one-node-inputs-output-only-if-inputs-are-different/67628/4 "2022-09-12T22:37:16Z")

</div>

I've seen some flows using the filter node but can't seem to know how to use it. It can do the part "block unless the value changes" but, where/how can I do the "block unless the value changes by n%" ?

![imagem](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/4/4/4478b8b036e70527465f157d1e12e476d3d7d177.png)

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<div class="post-metadata">

**Author:** ![hugovsky](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/hugovsky/32/67691_2.png) [@hugovsky](https://discourse.nodered.org/u/hugovsky)\
**Post date:** [12 September 2022 22:39 UTC](https://discourse.nodered.org/t/one-node-inputs-output-only-if-inputs-are-different/67628/5 "2022-09-12T22:39:08Z")

</div>

This is my current flow:

```auto
[{"id":"3085c8029a404c08","type":"api-call-service","z":"804ab9ebc9da9197","name":"Notifica TV","server":"e1926eef.58258","version":5,"debugenabled":false,"domain":"notify","service":"tv_sala","areaId":[],"deviceId":[],"entityId":[],"data":"{\"message\":\"A temperatura no exterior é de {{payload}}\"}","dataType":"json","mergeContext":"","mustacheAltTags":false,"outputProperties":[],"queue":"none","x":810,"y":580,"wires":[[]]},{"id":"6d0a40ac81937050","type":"api-current-state","z":"804ab9ebc9da9197","name":"Verifica Estado TV","server":"e1926eef.58258","version":3,"outputs":2,"halt_if":"on","halt_if_type":"str","halt_if_compare":"is","entity_id":"media_player.tv_sala","state_type":"str","blockInputOverrides":false,"outputProperties":[{"property":"payload","propertyType":"flow","value":"","valueType":"entityState"}],"for":0,"forType":"num","forUnits":"minutes","override_topic":false,"state_location":"payload","override_payload":"msg","entity_location":"data","override_data":"msg","x":630,"y":580,"wires":[["3085c8029a404c08"],[]]},{"id":"e04ecc6f9501148c","type":"poll-state","z":"804ab9ebc9da9197","name":"Temp","server":"e1926eef.58258","version":2,"exposeToHomeAssistant":false,"haConfig":[{"property":"name","value":""},{"property":"icon","value":""}],"updateinterval":"10","updateIntervalType":"num","updateIntervalUnits":"minutes","outputinitially":false,"outputonchanged":false,"entity_id":"sensor.temp_exterior","state_type":"str","halt_if":"","halt_if_type":"str","halt_if_compare":"is","outputs":1,"x":55.20000076293945,"y":577.5999755859375,"wires":[["bddb7f249a6576e3"]]},{"id":"bddb7f249a6576e3","type":"rbe","z":"804ab9ebc9da9197","name":"","func":"rbe","gap":"","start":"","inout":"out","septopics":true,"property":"payload","topi":"topic","x":270,"y":580,"wires":[["6d0a40ac81937050"]]},{"id":"e1926eef.58258","type":"server","name":"Home Assistant","version":4,"addon":true,"rejectUnauthorizedCerts":true,"ha_boolean":"y|yes|true|on|home|open","connectionDelay":true,"cacheJson":true,"heartbeat":false,"heartbeatInterval":30,"areaSelector":"friendlyName","deviceSelector":"friendlyName","entitySelector":"friendlyName","statusSeparator":"at: ","statusYear":"hidden","statusMonth":"short","statusDay":"numeric","statusHourCycle":"h23","statusTimeFormat":"h:m"}]

```

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<div class="post-metadata">

**Author:** ![hugovsky](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/hugovsky/32/67691_2.png) [@hugovsky](https://discourse.nodered.org/u/hugovsky)\
**Post date:** [12 September 2022 22:40 UTC](https://discourse.nodered.org/t/one-node-inputs-output-only-if-inputs-are-different/67628/6 "2022-09-12T22:40:25Z")

</div>

> [@E1cid](#):
>
> This should work
> 
> ```auto
> [{"id":"89faddb4.adcff","type":"inject","z":"aaa27ee4852b402b","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"20","payloadType":"num","x":110,"y":660,"wires":[["69d74780.c3706","d8105e11.a53ba8"]]},{"id":"69d74780.c3706","type":"rbe","z":"aaa27ee4852b402b","name":"","func":"rbe","gap":"","start":"","inout":"out","septopics":true,"property":"payload","x":330,"y":660,"wires":[["e5efcba5.436668"]]},{"id":"d8105e11.a53ba8","type":"join","z":"aaa27ee4852b402b","name":"","mode":"custom","build":"array","property":"payload","propertyType":"msg","key":"topic","joiner":"\\n","joinerType":"str","accumulate":false,"timeout":"","count":"3","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"","reduceFixup":"","x":330,"y":720,"wires":[["b91de405.26f66"]]},{"id":"defae9a4.8f94a","type":"inject","z":"aaa27ee4852b402b","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"21","payloadType":"num","x":110,"y":720,"wires":[["69d74780.c3706","d8105e11.a53ba8"]]},{"id":"e5efcba5.436668","type":"change","z":"aaa27ee4852b402b","name":"","rules":[{"t":"set","p":"complete","pt":"msg","to":"true","tot":"bool"}],"action":"","property":"","from":"","to":"","reg":false,"x":510,"y":660,"wires":[["d8105e11.a53ba8"]]},{"id":"b91de405.26f66","type":"change","z":"aaa27ee4852b402b","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"$.payload[-1]","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":520,"y":720,"wires":[["f5f3d227.61fc28"]]},{"id":"f5f3d227.61fc28","type":"debug","z":"aaa27ee4852b402b","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":730,"y":720,"wires":[]}]
> 
> ```
> 
> if 3 payloads the same it will output, or if payload changes it will output.

I only use 1 input. Your example seems to be useful for 2 different inputs.

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<div class="post-metadata">

**Author:** ![E1cid](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/e1cid/32/77971_2.png) [@E1cid](https://discourse.nodered.org/u/E1cid)\
**Post date:** [12 September 2022 22:41 UTC](https://discourse.nodered.org/t/one-node-inputs-output-only-if-inputs-are-different/67628/7 "2022-09-12T22:41:29Z")

</div>

It is two inject simulating different readings connect your HA node to both the filter and the join.

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<div class="post-metadata">

**Author:** ![hugovsky](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/hugovsky/32/67691_2.png) [@hugovsky](https://discourse.nodered.org/u/hugovsky)\
**Post date:** [12 September 2022 22:42 UTC](https://discourse.nodered.org/t/one-node-inputs-output-only-if-inputs-are-different/67628/8 "2022-09-12T22:42:15Z")

</div>

ahh... ok. Sorry. I didn't understood it

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<div class="post-metadata">

**Author:** ![jbudd](https://avatars.discourse-cdn.com/v4/letter/j/5f8ce5/32.png) [@jbudd](https://discourse.nodered.org/u/jbudd)\
**Post date:** [12 September 2022 22:50 UTC](https://discourse.nodered.org/t/one-node-inputs-output-only-if-inputs-are-different/67628/9 "2022-09-12T22:50:29Z")

</div>

> [@hugovsky](#):
>
> where/how can I do the "block unless the value changes by n%" ?

If you select "block unless value change is greater than", you can then enter eg "10%" and choose if the comparison should be with the last input or output value.

 ![Untitled 4](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/b/9/b93a2e4bf5c039e726a33bf5febfb691a47ac930.jpeg)

```auto
[{"id":"4d711fe85855c6fd","type":"rbe","z":"ac631a6e.90e038","name":"","func":"deadband","gap":"10%","start":"","inout":"in","septopics":true,"property":"payload","topi":"topic","x":520,"y":200,"wires":[["d1416f72b38a04d5"]]},{"id":"d1416f72b38a04d5","type":"debug","z":"ac631a6e.90e038","name":"debug 35","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":660,"y":200,"wires":[]},{"id":"2389ba4fd1a59acc","type":"inject","z":"ac631a6e.90e038","name":"120.9 (109.9 + 10.0001%)","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"120.9","payloadType":"num","x":310,"y":240,"wires":[["4d711fe85855c6fd"]]},{"id":"4d896c47c9651f4f","type":"inject","z":"ac631a6e.90e038","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"100","payloadType":"num","x":250,"y":160,"wires":[["4d711fe85855c6fd"]]},{"id":"c05ecea30a051b17","type":"inject","z":"ac631a6e.90e038","name":"109.9 (100 + 9.9%) ","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"109.9","payloadType":"num","x":290,"y":200,"wires":[["4d711fe85855c6fd"]]}]

```

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<div class="post-metadata">

**Author:** ![hugovsky](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/hugovsky/32/67691_2.png) [@hugovsky](https://discourse.nodered.org/u/hugovsky)\
**Post date:** [12 September 2022 22:51 UTC](https://discourse.nodered.org/t/one-node-inputs-output-only-if-inputs-are-different/67628/10 "2022-09-12T22:51:12Z")

</div>

@E1cid I've marked your answer as the solution. I does exactly what I wanted. Thank you.

@jbudd Thank you for your contribution, too.

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<div class="post-metadata">

**Author:** ![hugovsky](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/hugovsky/32/67691_2.png) [@hugovsky](https://discourse.nodered.org/u/hugovsky)\
**Post date:** [12 September 2022 22:53 UTC](https://discourse.nodered.org/t/one-node-inputs-output-only-if-inputs-are-different/67628/11 "2022-09-12T22:53:15Z")

</div>

SO much to learn... Thank you again.

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [26 September 2022 22:53 UTC](https://discourse.nodered.org/t/one-node-inputs-output-only-if-inputs-are-different/67628/12 "2022-09-26T22:53:45Z")

</div>

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