# General

**URL:** https://discourse.nodered.org/c/general/7.md?page=576

[Latest](https://discourse.nodered.org/latest.md) · [Categories](https://discourse.nodered.org/categories.md) · [Tags](https://discourse.nodered.org/tags.md)

**Page:** 577

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## [Why my nodered cannot detect USB device on my raspberrry pi](https://discourse.nodered.org/t/why-my-nodered-cannot-detect-usb-device-on-my-raspberrry-pi/43572)

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**Author:** [@alex1](https://discourse.nodered.org/u/alex1)\
**Replies:** 3\
**Last updated:** [2 April 2021 20:53 UTC](https://discourse.nodered.org/t/why-my-nodered-cannot-detect-usb-device-on-my-raspberrry-pi/43572 "2021-04-02T20:53:23Z")

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## [Inject node only fires if msg.payload is defined?](https://discourse.nodered.org/t/inject-node-only-fires-if-msg-payload-is-defined/43476)

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**Author:** [@Nodi.Rubrum](https://discourse.nodered.org/u/Nodi.Rubrum)\
**Replies:** 9\
**Last updated:** [2 April 2021 17:25 UTC](https://discourse.nodered.org/t/inject-node-only-fires-if-msg-payload-is-defined/43476 "2021-04-02T17:25:16Z")

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Inject node only fires if msg.payload defined? So, msg.payload as any value, inject node fires when clicked. But if msg.\* exists, but no msg.payload exits inject node does not fire. It is kind of a pain to add a chang…

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## [Suggestion, when exporting a specific flow, name the downloaded file to the name of the flow tab?](https://discourse.nodered.org/t/suggestion-when-exporting-a-specific-flow-name-the-downloaded-file-to-the-name-of-the-flow-tab/43566)

<div class="topic-metadata">

**Author:** [@Nodi.Rubrum](https://discourse.nodered.org/u/Nodi.Rubrum)\
**Replies:** 0\
**Last updated:** [2 April 2021 17:24 UTC](https://discourse.nodered.org/t/suggestion-when-exporting-a-specific-flow-name-the-downloaded-file-to-the-name-of-the-flow-tab/43566 "2021-04-02T17:24:48Z")

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Suggestion, when exporting a specific flow, entire flow on tab, name the downloaded file to the name of the flow tab? For example, if the active tab in the editor is 'my flow', if I do an export of that tab, name the fl…

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## [Node-Red connection with Emotiv Bcı](https://discourse.nodered.org/t/node-red-connection-with-emotiv-bci/43548)

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**Author:** [@engineerrules](https://discourse.nodered.org/u/engineerrules)\
**Replies:** 7\
**Last updated:** [2 April 2021 16:02 UTC](https://discourse.nodered.org/t/node-red-connection-with-emotiv-bci/43548 "2021-04-02T16:02:28Z")

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Hello Friends; How can ı connect with Node-Red and emotiv? Someone can say sth about it :confused:

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## [Catch Com S7 error](https://discourse.nodered.org/t/catch-com-s7-error/43557)

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**Author:** [@jolrom](https://discourse.nodered.org/u/jolrom)\
**Replies:** 1\
**Last updated:** [2 April 2021 15:46 UTC](https://discourse.nodered.org/t/catch-com-s7-error/43557 "2021-04-02T15:46:22Z")

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Hello, I'm using the palette node-red-contrib-s7 to collect data from a PLC S71500. The communication works nicely but I want to get the error if the connexion fail. For example if I unplug my PLC I see the error in th…

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## [Small engine dyno need help to reset my counter after run](https://discourse.nodered.org/t/small-engine-dyno-need-help-to-reset-my-counter-after-run/43215)

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**Author:** [@dirtydredrt](https://discourse.nodered.org/u/dirtydredrt)\
**Replies:** 75\
**Last updated:** [2 April 2021 14:28 UTC](https://discourse.nodered.org/t/small-engine-dyno-need-help-to-reset-my-counter-after-run/43215 "2021-04-02T14:28:35Z")

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Using a raspberry pi and a hall effects sensor to capture shaft rpm. this code will give me the rpm. but after a run i need to start over with zero rpm. this couter just keepd adding the rpm every test run My function…

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## [EXEC node can not change directory](https://discourse.nodered.org/t/exec-node-can-not-change-directory/43522)

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**Author:** [@sweetwater](https://discourse.nodered.org/u/sweetwater)\
**Replies:** 3\
**Last updated:** [2 April 2021 13:04 UTC](https://discourse.nodered.org/t/exec-node-can-not-change-directory/43522 "2021-04-02T13:04:53Z")

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Running NODE RED on a Raspberry PI and i have had great success with it . But there is one strange problem I am stuck on: I have a tar file called "dist.tar" in the directory called /home/pi/sweetwater/public When I …

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## [GPIO not available via NODE-RED](https://discourse.nodered.org/t/gpio-not-available-via-node-red/41814)

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**Author:** [@MFMF](https://discourse.nodered.org/u/MFMF)\
**Replies:** 5\
**Last updated:** [2 April 2021 11:16 UTC](https://discourse.nodered.org/t/gpio-not-available-via-node-red/41814 "2021-04-02T11:16:38Z")

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Hello together, i saw all topics which are similar to mine, but still have the problem that my GPIO In/Out Nodes in NODE-RED doesnt work anymore. I dont know why. Wheter i have wrong config or else. I can see the gpio …

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## [How to split an array without split node](https://discourse.nodered.org/t/how-to-split-an-array-without-split-node/43543)

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**Author:** [@ivexy24](https://discourse.nodered.org/u/ivexy24)\
**Replies:** 4\
**Last updated:** [2 April 2021 10:52 UTC](https://discourse.nodered.org/t/how-to-split-an-array-without-split-node/43543 "2021-04-02T10:52:16Z")

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I want to know how can I split an array without having to use the split node. I want to do it in the javascript file of my custom node.Thanks

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## [Multi MQTT and function](https://discourse.nodered.org/t/multi-mqtt-and-function/43537)

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**Author:** [@yingkhun](https://discourse.nodered.org/u/yingkhun)\
**Replies:** 7\
**Last updated:** [2 April 2021 10:05 UTC](https://discourse.nodered.org/t/multi-mqtt-and-function/43537 "2021-04-02T10:05:46Z")

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Hi I just started learning NodeRED I have some question about Multi MQTT input to function I have 5 MQTT subscribe topic value (update every 5 sec) stage (retained messages) auto (retained messages) max (retained …

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## [Exec stdout and SSH](https://discourse.nodered.org/t/exec-stdout-and-ssh/43532)

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**Author:** [@leftymuller](https://discourse.nodered.org/u/leftymuller)\
**Replies:** 4\
**Last updated:** [2 April 2021 08:19 UTC](https://discourse.nodered.org/t/exec-stdout-and-ssh/43532 "2021-04-02T08:19:58Z")

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G'Day all! I am SSH'ing to other pi's to get their CPU load and Temp It runs and gives output in a shell however node-red isnt seeing it because its not stdout it runs locally fine. ssh -l pi 192.168.2.246 top -d 0.5…

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## [Google Nest new setup](https://discourse.nodered.org/t/google-nest-new-setup/43538)

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**Author:** [@MagicGit](https://discourse.nodered.org/u/MagicGit)\
**Replies:** 0\
**Last updated:** [2 April 2021 08:19 UTC](https://discourse.nodered.org/t/google-nest-new-setup/43538 "2021-04-02T08:19:04Z")

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I'm new to using Google Nest Thermostat with Node-Red. I've created a new account and project with Google developers which differs from any of the examples I've found here. I've been allocated by Google OAuth client ID…

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## [Counter node loses count on upgrade](https://discourse.nodered.org/t/counter-node-loses-count-on-upgrade/43440)

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**Author:** [@mikefila](https://discourse.nodered.org/u/mikefila)\
**Replies:** 23\
**Last updated:** [2 April 2021 06:58 UTC](https://discourse.nodered.org/t/counter-node-loses-count-on-upgrade/43440 "2021-04-02T06:58:11Z")

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Hi, I've run into a problem where I lose my information from a counter node. The last 2 upgrades it's reset to it's initial value. I have context enabled in settings.js. I can see the file, the value is correct. I feel …

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## [Rebuilding Node-Red - stuck with requestor](https://discourse.nodered.org/t/rebuilding-node-red-stuck-with-requestor/43530)

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**Author:** [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)\
**Replies:** 1\
**Last updated:** [2 April 2021 06:18 UTC](https://discourse.nodered.org/t/rebuilding-node-red-stuck-with-requestor/43530 "2021-04-02T06:18:08Z")

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Alas last night a macine's SD card died. I have a backup of the flow/s but there are a lot of nodes which need installing. I'm guessing I may have to do it from the CLI, as this is what I see when I get to the GUI. An…

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## [Access from mobile phone](https://discourse.nodered.org/t/access-from-mobile-phone/43533)

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**Author:** [@Herbert](https://discourse.nodered.org/u/Herbert)\
**Replies:** 0\
**Last updated:** [2 April 2021 05:55 UTC](https://discourse.nodered.org/t/access-from-mobile-phone/43533 "2021-04-02T05:55:37Z")

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Hello, normally I change something in the Nodered (not in the Dashboar) from computer and from Android mobile phone. Since I secured the access from the IP:1880, I have no access from my mobile phone Chrome. I cannot …

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## [How to save data in variables to process them](https://discourse.nodered.org/t/how-to-save-data-in-variables-to-process-them/43531)

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**Author:** [@BrokenBeat](https://discourse.nodered.org/u/BrokenBeat)\
**Replies:** 3\
**Last updated:** [2 April 2021 03:15 UTC](https://discourse.nodered.org/t/how-to-save-data-in-variables-to-process-them/43531 "2021-04-02T03:15:22Z")

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I am using nodes "inject" as test data that would arrive every second, later using node "function" I am saving the data in different variables identifying them with the "msg.topic" to be able to identify the data, separa…

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## [Is it possible to run nr on a apache webserver?](https://discourse.nodered.org/t/is-it-possible-to-run-nr-on-a-apache-webserver/43498)

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**Author:** [@YT2310](https://discourse.nodered.org/u/YT2310)\
**Replies:** 3\
**Last updated:** [1 April 2021 21:46 UTC](https://discourse.nodered.org/t/is-it-possible-to-run-nr-on-a-apache-webserver/43498 "2021-04-01T21:46:50Z")

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Hey there, I m just wondering if its possible to run nr on a web server?

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## [Speedtest node error](https://discourse.nodered.org/t/speedtest-node-error/43265)

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**Author:** [@manjha](https://discourse.nodered.org/u/manjha)\
**Replies:** 22\
**Last updated:** [1 April 2021 21:25 UTC](https://discourse.nodered.org/t/speedtest-node-error/43265 "2021-04-01T21:25:50Z")

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Since several months, I run speedtest (the node) at 08:00 in the morning just to get a daity check on network performance. I do this on a Raspberry Pi 4B 8GB at home, but also on a R-Pi 3B in my vacation house. Both ins…

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## [Node-RED choose dynamically data series to visualize in embedded Grafana plots](https://discourse.nodered.org/t/node-red-choose-dynamically-data-series-to-visualize-in-embedded-grafana-plots/43504)

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**Author:** [@torrdan](https://discourse.nodered.org/u/torrdan)\
**Replies:** 2\
**Last updated:** [1 April 2021 20:29 UTC](https://discourse.nodered.org/t/node-red-choose-dynamically-data-series-to-visualize-in-embedded-grafana-plots/43504 "2021-04-01T20:29:04Z")

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Hi, I use node-red to collect measurements data from several sensors. I store those values in an influxDB database (each sensor is saved as a different field, e.g. temperature 1, pressure1, humidity1, etc..) and plot in…

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## [Basic help sending an MQTT payload via a slider](https://discourse.nodered.org/t/basic-help-sending-an-mqtt-payload-via-a-slider/43516)

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**Author:** [@jamesd256](https://discourse.nodered.org/u/jamesd256)\
**Replies:** 2\
**Last updated:** [1 April 2021 19:38 UTC](https://discourse.nodered.org/t/basic-help-sending-an-mqtt-payload-via-a-slider/43516 "2021-04-01T19:38:53Z")

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Hi, Just migrating a dashboard I had set up inside HA so that it becomes just an MQTT based version. In the HA version, I'm connecting a dashboard slider to a call service node, and can manipulate the payload on the ca…

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## [Trouble with function](https://discourse.nodered.org/t/trouble-with-function/43479)

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**Author:** [@mattk](https://discourse.nodered.org/u/mattk)\
**Replies:** 4\
**Last updated:** [1 April 2021 17:29 UTC](https://discourse.nodered.org/t/trouble-with-function/43479 "2021-04-01T17:29:05Z")

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Hi, IT guy pretending to understand how to script this function and not getting it. Below function is working. The reason I did it this way was to simply get the right output to BLYNK app. However there are some values…

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## [PiGPIOd Freezing or Stops Responding: How to Debug?](https://discourse.nodered.org/t/pigpiod-freezing-or-stops-responding-how-to-debug/43492)

<div class="topic-metadata">

**Author:** [@Noschvie](https://discourse.nodered.org/u/Noschvie)\
**Replies:** 4\
**Last updated:** [1 April 2021 17:16 UTC](https://discourse.nodered.org/t/pigpiod-freezing-or-stops-responding-how-to-debug/43492 "2021-04-01T17:16:15Z")

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Continuing the discussion from PiGPIOd Freezing or Stops Responding?: same here... @Nodi.Rubrum : did you get this resolved? RPi3+ with NR running as docker container (nodered/node-red:latest-12) and with an optocoupl…

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## [Sending and receiving info from serial port and download file](https://discourse.nodered.org/t/sending-and-receiving-info-from-serial-port-and-download-file/43414)

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**Author:** [@Lousa](https://discourse.nodered.org/u/Lousa)\
**Replies:** 3\
**Last updated:** [1 April 2021 17:05 UTC](https://discourse.nodered.org/t/sending-and-receiving-info-from-serial-port-and-download-file/43414 "2021-04-01T17:05:19Z")

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Hello! I'm new in node-red and i'm doing a project where i have a graphical interface with some numeric parameters to be inserted by the user, send to a serial port (mbed) and receive another information to the same ser…

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## [\[red\] Uncaught Exception: Pointers as to a starting point](https://discourse.nodered.org/t/red-uncaught-exception-pointers-as-to-a-starting-point/43242)

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**Author:** [@Diez66](https://discourse.nodered.org/u/Diez66)\
**Replies:** 2\
**Last updated:** [1 April 2021 16:44 UTC](https://discourse.nodered.org/t/red-uncaught-exception-pointers-as-to-a-starting-point/43242 "2021-04-01T16:44:13Z")

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OK, I see one of these each day and I have had a look around the forum and after trying to work out which node may be causing this I am stumped. Don't know how to proceed! I have tidied up my many flows and now they run…

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## [Node-Red & Mopidy](https://discourse.nodered.org/t/node-red-mopidy/41944)

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**Author:** [@mellow](https://discourse.nodered.org/u/mellow)\
**Replies:** 1\
**Last updated:** [1 April 2021 16:42 UTC](https://discourse.nodered.org/t/node-red-mopidy/41944 "2021-04-01T16:42:20Z")

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Hey y'all, I downloaded node-red-contrib-mopidy but I'm having no luck calling the method "tracklist.add". I am calling the method with the "uris" parameter (which is not deprecated), example: uris = \["spotify:track:4Oa…

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## [Timestamp converting](https://discourse.nodered.org/t/timestamp-converting/43461)

<div class="topic-metadata">

**Author:** [@Pecako2001](https://discourse.nodered.org/u/Pecako2001)\
**Replies:** 7\
**Last updated:** [1 April 2021 15:19 UTC](https://discourse.nodered.org/t/timestamp-converting/43461 "2021-04-01T15:19:51Z")

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Hello, I'm new to this forum so i dont know where to put this Topic. I have a problem. I'm trying to publish 2 variables from mqtt with corrensponding date and time into a CSV file. But the date and time i'm given wi…

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## [How to make condition with msg.payload = \[empty\]](https://discourse.nodered.org/t/how-to-make-condition-with-msg-payload-empty/19396)

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**Author:** [@Yortz](https://discourse.nodered.org/u/Yortz)\
**Replies:** 7\
**Last updated:** [1 April 2021 12:55 UTC](https://discourse.nodered.org/t/how-to-make-condition-with-msg-payload-empty/19396 "2021-04-01T12:55:32Z")

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Hi. I have a question. I select data from influxdb in 3 condition 1.now() 2.now() - 1d 3.now() - 7d My problem is when I tried to get data with \[ now() - 1d \] & \[ now() - 7d \] influx in node return empty msg.payload …

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## [Detecting "null" flow variables](https://discourse.nodered.org/t/detecting-null-flow-variables/14569)

<div class="topic-metadata">

**Author:** [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)\
**Replies:** 5\
**Last updated:** [1 April 2021 12:54 UTC](https://discourse.nodered.org/t/detecting-null-flow-variables/14569 "2021-04-01T12:54:34Z")

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I have this bit of code: var w = flow.get("who\_1") || {}; var p = msg.payload; if (w.length \> 0) { // do stuff here. The idea is that at/on first invocation the flow.get("who\_1") will not be set. I was under the …

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## [Only output a msg when the payload is in a different temperature range](https://discourse.nodered.org/t/only-output-a-msg-when-the-payload-is-in-a-different-temperature-range/43501)

<div class="topic-metadata">

**Author:** [@paulot88](https://discourse.nodered.org/u/paulot88)\
**Replies:** 2\
**Last updated:** [1 April 2021 10:23 UTC](https://discourse.nodered.org/t/only-output-a-msg-when-the-payload-is-in-a-different-temperature-range/43501 "2021-04-01T10:23:20Z")

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I have a switch node with different output depending on temperature range. Like 0-5, 5-10 and 10+ Now there is output when the temperature changes from 6 to 7 and 7 to 8. I want outputs only when there is a change in ra…

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## [Show ip camera in dashboard and store prefixed buffer video](https://discourse.nodered.org/t/show-ip-camera-in-dashboard-and-store-prefixed-buffer-video/39572)

<div class="topic-metadata">

**Author:** [@Lupin\_III](https://discourse.nodered.org/u/Lupin_III)\
**Replies:** 52\
**Last updated:** [1 April 2021 10:10 UTC](https://discourse.nodered.org/t/show-ip-camera-in-dashboard-and-store-prefixed-buffer-video/39572 "2021-04-01T10:10:44Z")

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Hi, what I'm achieving to do is display an IP camera on the dashboard and store a prefix buffer video when I need, but starting some seconds before my trigger. Thanks to all support inside the forum I'm able to display …

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