# General **URL:** https://discourse.nodered.org/c/general/7.md?page=710 [Latest](https://discourse.nodered.org/latest.md) · [Categories](https://discourse.nodered.org/categories.md) · [Tags](https://discourse.nodered.org/tags.md) **Page:** 711 --- ## [Function to dynamically change the MQTT topic based on user input](https://discourse.nodered.org/t/function-to-dynamically-change-the-mqtt-topic-based-on-user-input/30438)
**Author:** [@zazas321](https://discourse.nodered.org/u/zazas321)\ **Replies:** 13\ **Last updated:** [21 July 2020 09:40 UTC](https://discourse.nodered.org/t/function-to-dynamically-change-the-mqtt-topic-based-on-user-input/30438 "2020-07-21T09:40:03Z")
I have a flow where user inputs data through dropdown and form menus. I save this data in flow variable as such: flow.DBdata\[0\] = Device flow.DBdata\[1\] = Item flow.DBdata\[2\] = Serial What I need to do is to join DBda… --- ## [Extract audio data from usb sound card (rpi)](https://discourse.nodered.org/t/extract-audio-data-from-usb-sound-card-rpi/30447)
**Author:** [@yzerman](https://discourse.nodered.org/u/yzerman)\ **Replies:** 4\ **Last updated:** [21 July 2020 09:23 UTC](https://discourse.nodered.org/t/extract-audio-data-from-usb-sound-card-rpi/30447 "2020-07-21T09:23:52Z")
Hello, could you please give me suggestion how i can get audio from usb sound card into node-red. I use my phone as audio source and plug the audio jack into usb sound card connected to one of the raspberry's usb ports. … --- ## [(Brain failure) Need help understanding why it isn't working](https://discourse.nodered.org/t/brain-failure-need-help-understanding-why-it-isnt-working/30440)
**Author:** [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)\ **Replies:** 20\ **Last updated:** [21 July 2020 09:20 UTC](https://discourse.nodered.org/t/brain-failure-need-help-understanding-why-it-isnt-working/30440 "2020-07-21T09:20:16Z")
I am trying to optimise how a msg is constructed. This is what I have: if (counter == 0) { msg = { payload: "OFF", icon: '\\ **Author:** [@shipra](https://discourse.nodered.org/u/shipra)\ **Replies:** 1\ **Last updated:** [21 July 2020 08:08 UTC](https://discourse.nodered.org/t/not-getting-updated-data-back-to-my-database/30444 "2020-07-21T08:08:40Z") Sir, i have deployed mqtt rfid node where i am giving rfid number if its valid it shows CR\_SUCCESS otherwise CR\_FAIL .Now i have a door controller which has 2 switch open and close i want whenever anyone comes with valid… --- ## [Gateway data to a file](https://discourse.nodered.org/t/gateway-data-to-a-file/30443)
**Author:** [@Roger](https://discourse.nodered.org/u/Roger)\ **Replies:** 0\ **Last updated:** [21 July 2020 07:22 UTC](https://discourse.nodered.org/t/gateway-data-to-a-file/30443 "2020-07-21T07:22:23Z")
Hello, I configured a temperature sensor with my arduino and I send the data to my gateway (multitech conduit). Now with node-red I need to get this data and save it in a file (xlsx or similar). I intend to receive the… --- ## [Search database rows in msg object](https://discourse.nodered.org/t/search-database-rows-in-msg-object/30386)
**Author:** [@reloopbenny](https://discourse.nodered.org/u/reloopbenny)\ **Replies:** 7\ **Last updated:** [21 July 2020 05:46 UTC](https://discourse.nodered.org/t/search-database-rows-in-msg-object/30386 "2020-07-21T05:46:08Z")
Hello! I have a converted XML in node red and formated to node-red array with JSONata. I have database same formated output with JSONata. my xml output in "msg.xmloutput" and my database output in "msg.dboutput" I … --- ## [Two msg in delay with function node](https://discourse.nodered.org/t/two-msg-in-delay-with-function-node/30435)
**Author:** [@lalo](https://discourse.nodered.org/u/lalo)\ **Replies:** 3\ **Last updated:** [21 July 2020 05:04 UTC](https://discourse.nodered.org/t/two-msg-in-delay-with-function-node/30435 "2020-07-21T05:04:10Z")
Hi guys, I'm trying to send two messages from one funcion it's kind off something like this.... msg.payload = "hi"; msg.delay = 5000; msg.payload = "goodbye"; msg.delay = 10000; return msg; basically I have a msg to se… --- ## [Ethernet and WiFi at the same time?](https://discourse.nodered.org/t/ethernet-and-wifi-at-the-same-time/30091)
**Author:** [@JordanHamann](https://discourse.nodered.org/u/JordanHamann)\ **Replies:** 11\ **Last updated:** [21 July 2020 03:46 UTC](https://discourse.nodered.org/t/ethernet-and-wifi-at-the-same-time/30091 "2020-07-21T03:46:36Z")
Hi everyone, I'm pretty new to all of this so please excuse my ignorance. I'm running Node-Red on a Raspberry Pi 4 (Standard Raspbian Operating System) and I'm trying to retrieve some data from a PLC and then send that… --- ## [Json show records on table](https://discourse.nodered.org/t/json-show-records-on-table/30216)
**Author:** [@lalo](https://discourse.nodered.org/u/lalo)\ **Replies:** 6\ **Last updated:** [21 July 2020 02:31 UTC](https://discourse.nodered.org/t/json-show-records-on-table/30216 "2020-07-21T02:31:50Z")
Hi, guys I'm trying to recover and show my datafrom a json file on the dashboard but I don't know what is the problem. This is my flow \[{"id":"cb5a86a8.addd98","type":"ui\_template","z":"1c449847.08bad8","group":"f8e166… --- ## [Execution of a flow before NR shutdown?](https://discourse.nodered.org/t/execution-of-a-flow-before-nr-shutdown/30415)
**Author:** [@Nodi.Rubrum](https://discourse.nodered.org/u/Nodi.Rubrum)\ **Replies:** 3\ **Last updated:** [21 July 2020 01:07 UTC](https://discourse.nodered.org/t/execution-of-a-flow-before-nr-shutdown/30415 "2020-07-21T01:07:55Z")
Execution of a flow before NR shutdown? I thought I saw a forum thread on this? But I can't seem to find it, so maybe this is not possible currently? Since I am running a primary and secondary NR setup, not a cluster,… --- ## [Crelay and Sainsmart USB relays](https://discourse.nodered.org/t/crelay-and-sainsmart-usb-relays/30430)
**Author:** [@VA3CW](https://discourse.nodered.org/u/VA3CW)\ **Replies:** 0\ **Last updated:** [21 July 2020 00:49 UTC](https://discourse.nodered.org/t/crelay-and-sainsmart-usb-relays/30430 "2020-07-21T00:49:07Z")
Hi all! I've got Node-RED installed on a RPi4 and am using it to control a Sainsmart USB (FTDI) relay board. So far things seem to work with crelay however I'm suspicious that my approach is less than an efficient use … --- ## [Update Template On Set Schedule, Cache Results](https://discourse.nodered.org/t/update-template-on-set-schedule-cache-results/30427)
**Author:** [@Majerus1223](https://discourse.nodered.org/u/Majerus1223)\ **Replies:** 3\ **Last updated:** [20 July 2020 23:28 UTC](https://discourse.nodered.org/t/update-template-on-set-schedule-cache-results/30427 "2020-07-20T23:28:10Z")
Is there a way to have a template updated once, then for calls following the initial load just return the same data? I am attempting to have a schedule kick off at 12am, gather data then update the said template. When o… --- ## [Problems with mqtt node (msg.payload interrupt)](https://discourse.nodered.org/t/problems-with-mqtt-node-msg-payload-interrupt/30167)
**Author:** [@lalo](https://discourse.nodered.org/u/lalo)\ **Replies:** 14\ **Last updated:** [20 July 2020 21:54 UTC](https://discourse.nodered.org/t/problems-with-mqtt-node-msg-payload-interrupt/30167 "2020-07-20T21:54:28Z")
Hi, I'm trying to use some conditions with some readings from Arduino Mega, my issue is when I try to use the switch to send open, my condition don't allow me to send the msg, there is any solution to this? I was thinki… --- ## ["The flows on the server have been updated" with Pi gpiod nodes](https://discourse.nodered.org/t/the-flows-on-the-server-have-been-updated-with-pi-gpiod-nodes/29827)
**Author:** [@Charry2014](https://discourse.nodered.org/u/Charry2014)\ **Replies:** 18\ **Last updated:** [20 July 2020 21:39 UTC](https://discourse.nodered.org/t/the-flows-on-the-server-have-been-updated-with-pi-gpiod-nodes/29827 "2020-07-20T21:39:50Z")
My project is running on a Raspberry Pi 4, with Node Red running in Docker and I am deploying this to the Pi through Balena io. The project has two Docker images - one running the Pi GPIOD and the other running Node Red.… --- ## [Node-red-contrib-ewelink](https://discourse.nodered.org/t/node-red-contrib-ewelink/19195)
**Author:** [@JoseGodinho](https://discourse.nodered.org/u/JoseGodinho)\ **Replies:** 13\ **Last updated:** [20 July 2020 20:46 UTC](https://discourse.nodered.org/t/node-red-contrib-ewelink/19195 "2020-07-20T20:46:54Z")
Hello After installing the above mentioned node, and feeding with the credentials I get the Following error message "RequestError: Error: getaddrinfo ENOTFOUND europe-api.coolkit.cc" could be the region? if so how I… --- ## [PYNODE RED async message responses](https://discourse.nodered.org/t/pynode-red-async-message-responses/30409)
**Author:** [@shanajira](https://discourse.nodered.org/u/shanajira)\ **Replies:** 9\ **Last updated:** [20 July 2020 20:24 UTC](https://discourse.nodered.org/t/pynode-red-async-message-responses/30409 "2020-07-20T20:24:40Z")
hello I am using successfully pynodered (Python node red) to do a lot of processing in the background for all my node-red needs. Now I am trying to add "async" asynchronous functionality to my backend system via pynode… --- ## [Switch Node Sequence Rules](https://discourse.nodered.org/t/switch-node-sequence-rules/30405)
**Author:** [@n61ab](https://discourse.nodered.org/u/n61ab)\ **Replies:** 4\ **Last updated:** [20 July 2020 19:16 UTC](https://discourse.nodered.org/t/switch-node-sequence-rules/30405 "2020-07-20T19:16:02Z")
I have imported a flow that uses the Switch Node in a way I want to understand what it does. I am looking for information on how to use the "Sequence Rules" in the Switch Node. More specifically the "Index Between" rul… --- ## [TCP Data to csv file](https://discourse.nodered.org/t/tcp-data-to-csv-file/30411)
**Author:** [@valmik](https://discourse.nodered.org/u/valmik)\ **Replies:** 0\ **Last updated:** [20 July 2020 17:58 UTC](https://discourse.nodered.org/t/tcp-data-to-csv-file/30411 "2020-07-20T17:58:15Z")
Hello , From IoT sensor I am getting data over GPRS ( TCP ) format and able to create csv file by using TCP,CSV,SPLIT & FILE node I am getting below format in csv file $SLU355000082004871 06 430 200720162523 01 nu… --- ## [SHT20 Digital Thermostat](https://discourse.nodered.org/t/sht20-digital-thermostat/30399)
**Author:** [@Ki-va](https://discourse.nodered.org/u/Ki-va)\ **Replies:** 8\ **Last updated:** [20 July 2020 16:29 UTC](https://discourse.nodered.org/t/sht20-digital-thermostat/30399 "2020-07-20T16:29:02Z")
hi, I bought an SHT20 Digital Thermostat Temperature Humidity Controller Sensor and I'm having prombems connecting it to NR. The sensor have 4 wires: 3.3V SDA SCL GND I've connected the wires accordingly to the RP… --- ## [Lora to excel with nodered](https://discourse.nodered.org/t/lora-to-excel-with-nodered/30390)
**Author:** [@perico](https://discourse.nodered.org/u/perico)\ **Replies:** 3\ **Last updated:** [20 July 2020 16:27 UTC](https://discourse.nodered.org/t/lora-to-excel-with-nodered/30390 "2020-07-20T16:27:39Z")
Hello everybody, I get the data of my gateway with Lora node, but now I need to save this data (temperatures) in a Excel file. I'm using the nodes of the picture below, I've tried with and without csv node, but nothing… --- ## [Error installing node-red-contrib-modbus](https://discourse.nodered.org/t/error-installing-node-red-contrib-modbus/30395)
**Author:** [@josebelzam](https://discourse.nodered.org/u/josebelzam)\ **Replies:** 4\ **Last updated:** [20 July 2020 16:09 UTC](https://discourse.nodered.org/t/error-installing-node-red-contrib-modbus/30395 "2020-07-20T16:09:49Z")
Hi all, I'm trying to install node-red-contrib-modbus on my linux based PLC but it seems like I have a problem with the serial port configuration (I'm not sure). Bellow is the error code Could someone help me? Thanks… --- ## [Developing REST APIs using Node-red for a web application](https://discourse.nodered.org/t/developing-rest-apis-using-node-red-for-a-web-application/30392)
**Author:** [@kushan-athukorala](https://discourse.nodered.org/u/kushan-athukorala)\ **Replies:** 3\ **Last updated:** [20 July 2020 14:33 UTC](https://discourse.nodered.org/t/developing-rest-apis-using-node-red-for-a-web-application/30392 "2020-07-20T14:33:16Z")
I know that Node-red can be used to create and expose REST APIs easily. It uses nodejs and express internally to expose the REST services. I am planning to develop a node-red and mongodb backed REST APIs for a commercia… --- ## [Callback in Node red](https://discourse.nodered.org/t/callback-in-node-red/5919)
**Author:** [@akhilendharreddy](https://discourse.nodered.org/u/akhilendharreddy)\ **Replies:** 8\ **Last updated:** [20 July 2020 13:49 UTC](https://discourse.nodered.org/t/callback-in-node-red/5919 "2020-07-20T13:49:16Z")
I have lot of flows in my node red project, i want to track each and every flow, after success of each flow i want do some action like store data in db flow1 successfully injected , how can track each and every flow? --- ## [Help with Example of hdl-automation-nodered use](https://discourse.nodered.org/t/help-with-example-of-hdl-automation-nodered-use/30404)
**Author:** [@tenabiker](https://discourse.nodered.org/u/tenabiker)\ **Replies:** 0\ **Last updated:** [20 July 2020 13:43 UTC](https://discourse.nodered.org/t/help-with-example-of-hdl-automation-nodered-use/30404 "2020-07-20T13:43:55Z")
Hello, I'm very new to nodered community and I'm facing many difficulties using this node (which connects to the equipment I'm working this days). If someone could share a simple project, it will be great for my learni… --- ## [How to recognize doorbell sound](https://discourse.nodered.org/t/how-to-recognize-doorbell-sound/29360)
**Author:** [@janvda](https://discourse.nodered.org/u/janvda)\ **Replies:** 18\ **Last updated:** [20 July 2020 13:15 UTC](https://discourse.nodered.org/t/how-to-recognize-doorbell-sound/29360 "2020-07-20T13:15:48Z")
I would like to connect my doorbell (see picture) to the internet. ... but I would like to do that in a bit special way. The idea: In my living room I am having a AIY Voice Kit (= raspberry pi with micro and speaker… --- ## ['Persistent Context' variable names and 'Projects'...something to remember](https://discourse.nodered.org/t/persistent-context-variable-names-and-projects-something-to-remember/11614)
**Author:** [@zenofmud](https://discourse.nodered.org/u/zenofmud)\ **Replies:** 11\ **Last updated:** [20 July 2020 12:42 UTC](https://discourse.nodered.org/t/persistent-context-variable-names-and-projects-something-to-remember/11614 "2020-07-20T12:42:01Z")
There is some thing you should keep in mind when using projects and your flow is using 'Persistent Context' - the name of your variable. Say you have project called 'greenhouse' and you create a global persistent contex… --- ## [How many ports can be used in Node-Red?](https://discourse.nodered.org/t/how-many-ports-can-be-used-in-node-red/30382)
**Author:** [@MadanKumar](https://discourse.nodered.org/u/MadanKumar)\ **Replies:** 5\ **Last updated:** [20 July 2020 12:08 UTC](https://discourse.nodered.org/t/how-many-ports-can-be-used-in-node-red/30382 "2020-07-20T12:08:31Z")
Hello, This is Madan Kumar. i have a query that how many Ports can be used in Node-Red? is there any restrictions? or only Multiple ports can be used?? will be waiting for your reply. Thanks&Regards, M.Madan Kumar. --- ## [Building a 3 element array from "form" and "dropdown" nodes to send on button click](https://discourse.nodered.org/t/building-a-3-element-array-from-form-and-dropdown-nodes-to-send-on-button-click/30385)
**Author:** [@zazas321](https://discourse.nodered.org/u/zazas321)\ **Replies:** 10\ **Last updated:** [20 July 2020 11:50 UTC](https://discourse.nodered.org/t/building-a-3-element-array-from-form-and-dropdown-nodes-to-send-on-button-click/30385 "2020-07-20T11:50:05Z")
Hello. I am trying to figure out the most logical way to build a 3 element payload array and out of form and dropdown nodes. 1 variable comes from "dropdown" node ( "Device") 2 variables comes from "form" node ("Item"… --- ## [Questions from a Newbie - Looking for Help](https://discourse.nodered.org/t/questions-from-a-newbie-looking-for-help/29659)
**Author:** [@oncdastan](https://discourse.nodered.org/u/oncdastan)\ **Replies:** 25\ **Last updated:** [20 July 2020 11:13 UTC](https://discourse.nodered.org/t/questions-from-a-newbie-looking-for-help/29659 "2020-07-20T11:13:51Z")
Hi. I am new to Node-Red, and haven't done much with Pi. In my current project, I came across a few problems. Most of them are solved, thanks to this forum. Now, I have 4 problems left: 1- Starting Node-Red at boot, an… --- ## [Delay node problem with override](https://discourse.nodered.org/t/delay-node-problem-with-override/8687)
**Author:** [@ratomas](https://discourse.nodered.org/u/ratomas)\ **Replies:** 16\ **Last updated:** [20 July 2020 08:42 UTC](https://discourse.nodered.org/t/delay-node-problem-with-override/8687 "2020-07-20T08:42:58Z")
Hi. I tried to set override for delay. When I have msg.payload = true ( without delay ), for msg.payload = false ( defined delay ). Off delay works without problem, but for on delay I have at beginning flip-flop signal … [Previous page](https://discourse.nodered.org/c/general/7.md?page=709) [Next page](https://discourse.nodered.org/c/general/7.md?page=711)