# General

**URL:** https://discourse.nodered.org/c/general/7.md?page=709

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

**Page:** 710

---

## [Overlay text onto image](https://discourse.nodered.org/t/overlay-text-onto-image/16011)

<div class="topic-metadata">

**Author:** [@m\_elias](https://discourse.nodered.org/u/m_elias)\
**Replies:** 5\
**Last updated:** [22 July 2020 12:12 UTC](https://discourse.nodered.org/t/overlay-text-onto-image/16011 "2020-07-22T12:12:22Z")

</div>

I've been unable to find any examples online of how to overlay text onto an image. I'm using a http request node to return a binary buffer from an IP camera. Then I'm formatting the date/time (contrib-moment), setting th…

---

## [Using global array variables in template](https://discourse.nodered.org/t/using-global-array-variables-in-template/30461)

<div class="topic-metadata">

**Author:** [@panepoide](https://discourse.nodered.org/u/panepoide)\
**Replies:** 3\
**Last updated:** [22 July 2020 11:13 UTC](https://discourse.nodered.org/t/using-global-array-variables-in-template/30461 "2020-07-22T11:13:31Z")

</div>

Hi, I have a project where I store some sensor values in an array in order to print in the dashboard. These values come from one single sensor, so the array is some kind of history. Then, in another flow, I would like t…

---

## [Flow and global variables inaccessible when using dot notation](https://discourse.nodered.org/t/flow-and-global-variables-inaccessible-when-using-dot-notation/30539)

<div class="topic-metadata">

**Author:** [@lightbluecrab](https://discourse.nodered.org/u/lightbluecrab)\
**Replies:** 2\
**Last updated:** [22 July 2020 11:08 UTC](https://discourse.nodered.org/t/flow-and-global-variables-inaccessible-when-using-dot-notation/30539 "2020-07-22T11:08:22Z")

</div>

Hello again, I am looking for a way of accessing global/flow variables inside nodes (such as inside the URL of an http-request-node). So I used a change-node to set global.test but it remains "undefined" when I try to a…

---

## [Trigger output if value unchanged for X amount of time](https://discourse.nodered.org/t/trigger-output-if-value-unchanged-for-x-amount-of-time/30347)

<div class="topic-metadata">

**Author:** [@Mobile\_NR\_Env](https://discourse.nodered.org/u/Mobile_NR_Env)\
**Replies:** 4\
**Last updated:** [22 July 2020 09:38 UTC](https://discourse.nodered.org/t/trigger-output-if-value-unchanged-for-x-amount-of-time/30347 "2020-07-22T09:38:16Z")

</div>

Hello! I have a numerical sensor value Node-Red is reading from an MQTT topic. Unfortunately the script writing the MQTT topic freezes at times. This flow needs to be stopped if that happens! I'd like to be able to tr…

---

## [Solution for multiple users at the same time](https://discourse.nodered.org/t/solution-for-multiple-users-at-the-same-time/30437)

<div class="topic-metadata">

**Author:** [@zazas321](https://discourse.nodered.org/u/zazas321)\
**Replies:** 6\
**Last updated:** [22 July 2020 10:11 UTC](https://discourse.nodered.org/t/solution-for-multiple-users-at-the-same-time/30437 "2020-07-22T10:11:31Z")

</div>

Hello. I am making user interface for a pick to light project. I am controlling many ESP32/ESP8266 devices using node-red (reading sensor values,toggling GPIOS, monitoring device state and etc. The problem is that multip…

---

## [Efficiently subscribe to multiple MQTT topics using one MQTT node](https://discourse.nodered.org/t/efficiently-subscribe-to-multiple-mqtt-topics-using-one-mqtt-node/30527)

<div class="topic-metadata">

**Author:** [@zazas321](https://discourse.nodered.org/u/zazas321)\
**Replies:** 6\
**Last updated:** [22 July 2020 09:27 UTC](https://discourse.nodered.org/t/efficiently-subscribe-to-multiple-mqtt-topics-using-one-mqtt-node/30527 "2020-07-22T09:27:02Z")

</div>

Hey. I need to subscribe to multiple MQTT topics using a single MQTT node. Is that a good way to simplify the flow as I do not want to create a MQTT subscribtion node for every remote device that I have. I might have 50…

---

## [Tesseract - How to send input in tesseract node when we have to read data from Image](https://discourse.nodered.org/t/tesseract-how-to-send-input-in-tesseract-node-when-we-have-to-read-data-from-image/30479)

<div class="topic-metadata">

**Author:** [@anr8115](https://discourse.nodered.org/u/anr8115)\
**Replies:** 1\
**Last updated:** [21 July 2020 21:57 UTC](https://discourse.nodered.org/t/tesseract-how-to-send-input-in-tesseract-node-when-we-have-to-read-data-from-image/30479 "2020-07-21T21:57:04Z")

</div>

I have an image with data in it and iam trying to use tesseract node to read the data. Can you please let me know what should be input (Name ) in tesseract node and also how to load the image file to node-red inorder to …

---

## [Problem with OPC UA server](https://discourse.nodered.org/t/problem-with-opc-ua-server/30473)

<div class="topic-metadata">

**Author:** [@Holko](https://discourse.nodered.org/u/Holko)\
**Replies:** 2\
**Last updated:** [21 July 2020 21:50 UTC](https://discourse.nodered.org/t/problem-with-opc-ua-server/30473 "2020-07-21T21:50:12Z")

</div>

Hello! I'm working on my masters thesis in a local Siemens internship and part of the task is to use an IOT2040 as a sort of "gateway" between an ET200S (standing in for an S7-300) and an OPC UA client - since the forme…

---

## [MQTT gif Payload](https://discourse.nodered.org/t/mqtt-gif-payload/30499)

<div class="topic-metadata">

**Author:** [@gbos3415](https://discourse.nodered.org/u/gbos3415)\
**Replies:** 13\
**Last updated:** [21 July 2020 21:31 UTC](https://discourse.nodered.org/t/mqtt-gif-payload/30499 "2020-07-21T21:31:46Z")

</div>

Hello, So i recently bought Synology NAS where current I'm running my HA and node-red and plus my Synology Survalion system. finally this week I setup the telegram system on my SS and HA and everything is working the on…

---

## [Settings file nonexistant after install](https://discourse.nodered.org/t/settings-file-nonexistant-after-install/30506)

<div class="topic-metadata">

**Author:** [@FrancoisStArnaud](https://discourse.nodered.org/u/FrancoisStArnaud)\
**Replies:** 5\
**Last updated:** [21 July 2020 20:42 UTC](https://discourse.nodered.org/t/settings-file-nonexistant-after-install/30506 "2020-07-21T20:42:13Z")

</div>

Hi, I am new to Node-RED, sorry if this has been answered elsewhere, I couldn't find the answer. So, I just installed Node-Red, following the instructions from the Getting Started page (https://nodered.org/docs/getting-…

---

## [Redirect to URL using dashboard button](https://discourse.nodered.org/t/redirect-to-url-using-dashboard-button/30492)

<div class="topic-metadata">

**Author:** [@lightbluecrab](https://discourse.nodered.org/u/lightbluecrab)\
**Replies:** 1\
**Last updated:** [21 July 2020 20:02 UTC](https://discourse.nodered.org/t/redirect-to-url-using-dashboard-button/30492 "2020-07-21T20:02:40Z")

</div>

Hello everyone, I want to add a button to my node red dashboard that redirects you to an external URL (such as google.com). I read several threads on how to solve that issue, but I would like to use the node-red-dashboa…

---

## [Flow to decode binary data and a walk-through on how to install the npm module](https://discourse.nodered.org/t/flow-to-decode-binary-data-and-a-walk-through-on-how-to-install-the-npm-module/5174)

<div class="topic-metadata">

**Author:** [@Andrei](https://discourse.nodered.org/u/Andrei)\
**Replies:** 12\
**Last updated:** [21 July 2020 19:16 UTC](https://discourse.nodered.org/t/flow-to-decode-binary-data-and-a-walk-through-on-how-to-install-the-npm-module/5174 "2020-07-21T19:16:44Z")

</div>

I just wanted to share a simple way to parse and decode a binary stream of data using the npm module binary-parser-encoder. This is an alternative to the node-red-contrib-binary node 1- Install the module , in my case …

---

## [Stop node from initialization?](https://discourse.nodered.org/t/stop-node-from-initialization/30372)

<div class="topic-metadata">

**Author:** [@Nodi.Rubrum](https://discourse.nodered.org/u/Nodi.Rubrum)\
**Replies:** 9\
**Last updated:** [21 July 2020 17:11 UTC](https://discourse.nodered.org/t/stop-node-from-initialization/30372 "2020-07-21T17:11:04Z")

</div>

I suspect I know the answer, but is there a way to stop a node from initializing its self? Not unless the node developer allows it by design, right? I have a situation where I only want a node to 'initialize' when the …

---

## [Need to design aflow that every 30 min bursts X message with a 30ms interval](https://discourse.nodered.org/t/need-to-design-aflow-that-every-30-min-bursts-x-message-with-a-30ms-interval/30486)

<div class="topic-metadata">

**Author:** [@bioshock2k](https://discourse.nodered.org/u/bioshock2k)\
**Replies:** 10\
**Last updated:** [21 July 2020 16:30 UTC](https://discourse.nodered.org/t/need-to-design-aflow-that-every-30-min-bursts-x-message-with-a-30ms-interval/30486 "2020-07-21T16:30:57Z")

</div>

Hello dear forum users, I am testing a equipment and need to make a flow that every 30 min burst Xmessages i have already saved on a variable in a 30 ms interval between them. I can make one that sends messages every 3…

---

## [Connection Lost After Some Time](https://discourse.nodered.org/t/connection-lost-after-some-time/30000)

<div class="topic-metadata">

**Author:** [@oncdastan](https://discourse.nodered.org/u/oncdastan)\
**Replies:** 55\
**Last updated:** [21 July 2020 16:06 UTC](https://discourse.nodered.org/t/connection-lost-after-some-time/30000 "2020-07-21T16:06:46Z")

</div>

Hi. Project works fine for a while, nearly an hour, then, it says "Connection Lost". I try to deploy again, but it never happens. Says "no response from server". I reboor/shutdown, and I see an empty flow named "Flow 1".…

---

## [Node red email send failed](https://discourse.nodered.org/t/node-red-email-send-failed/30483)

<div class="topic-metadata">

**Author:** [@tadi](https://discourse.nodered.org/u/tadi)\
**Replies:** 4\
**Last updated:** [21 July 2020 15:41 UTC](https://discourse.nodered.org/t/node-red-email-send-failed/30483 "2020-07-21T15:41:23Z")

</div>

I've been trying to send an email using the node-red-node-email but no response anyone could help to fix the issue ?

---

## [Using SQLite Data Base for temporary data](https://discourse.nodered.org/t/using-sqlite-data-base-for-temporary-data/30463)

<div class="topic-metadata">

**Author:** [@e-Duardo](https://discourse.nodered.org/u/e-Duardo)\
**Replies:** 3\
**Last updated:** [21 July 2020 14:59 UTC](https://discourse.nodered.org/t/using-sqlite-data-base-for-temporary-data/30463 "2020-07-21T14:59:36Z")

</div>

I am starting to use SQLite for storing some values from a continuous flow of input data. My purpose is that the data storage is temporary, and I don't want de DB file to grow forever. Is there any SQL command (or any …

---

## [Dashboard input for upper and lower threshold hysteresis](https://discourse.nodered.org/t/dashboard-input-for-upper-and-lower-threshold-hysteresis/30420)

<div class="topic-metadata">

**Author:** [@Dom\_Nate](https://discourse.nodered.org/u/Dom_Nate)\
**Replies:** 12\
**Last updated:** [21 July 2020 14:29 UTC](https://discourse.nodered.org/t/dashboard-input-for-upper-and-lower-threshold-hysteresis/30420 "2020-07-21T14:29:54Z")

</div>

Hi, I am controlling a peltier heating element in conjunction with a thermometer to regulate the temperature of a heat exchanger using node-red-contrib-hysteresis. It works perfectly but it requires the upper and lower …

---

## [Failed Serial Transmission Arduino-Node RED: COM4 Access Denied](https://discourse.nodered.org/t/failed-serial-transmission-arduino-node-red-com4-access-denied/30481)

<div class="topic-metadata">

**Author:** [@MarkParents](https://discourse.nodered.org/u/MarkParents)\
**Replies:** 2\
**Last updated:** [21 July 2020 14:25 UTC](https://discourse.nodered.org/t/failed-serial-transmission-arduino-node-red-com4-access-denied/30481 "2020-07-21T14:25:38Z")

</div>

Hi everyone. I'm struggling with this problem: I have programmed my Arduino Uno for trasmitting via USB Serial communication the temperature measured by a temperature sensor connected to one of the Analog inputs of the A…

---

## [Light-scheduler node](https://discourse.nodered.org/t/light-scheduler-node/30470)

<div class="topic-metadata">

**Author:** [@aabbas](https://discourse.nodered.org/u/aabbas)\
**Replies:** 3\
**Last updated:** [21 July 2020 14:23 UTC](https://discourse.nodered.org/t/light-scheduler-node/30470 "2020-07-21T14:23:37Z")

</div>

Hi, I am using light-scheduler node to turn on/off my lights. It works but I get "Failed to interpret incoming msg.payload. Ignoring it!" instead True and False. Have any idea about this problem? Thank you

---

## [Deleting and Creating New Data Files](https://discourse.nodered.org/t/deleting-and-creating-new-data-files/30451)

<div class="topic-metadata">

**Author:** [@edwardr](https://discourse.nodered.org/u/edwardr)\
**Replies:** 11\
**Last updated:** [21 July 2020 13:37 UTC](https://discourse.nodered.org/t/deleting-and-creating-new-data-files/30451 "2020-07-21T13:37:48Z")

</div>

I\`m trying to find a way for data to be written to a file, so that when the file gets too big the file is either, stored, deleted and new file is put in its place? So far Ive found a way to write to a file, however Im u…

---

## [Show an image on the dashboard](https://discourse.nodered.org/t/show-an-image-on-the-dashboard/30466)

<div class="topic-metadata">

**Author:** [@Hattori](https://discourse.nodered.org/u/Hattori)\
**Replies:** 3\
**Last updated:** [21 July 2020 13:30 UTC](https://discourse.nodered.org/t/show-an-image-on-the-dashboard/30466 "2020-07-21T13:30:42Z")

</div>

I have an image of size 1280x800 contained in an Array. The Array is one dimensional with length 1280x800. I would like to be able to plot the corresponding image in the dashboard. I saw examples that loads the image fro…

---

## [UR robot TCP server](https://discourse.nodered.org/t/ur-robot-tcp-server/30424)

<div class="topic-metadata">

**Author:** [@rowen826](https://discourse.nodered.org/u/rowen826)\
**Replies:** 2\
**Last updated:** [21 July 2020 13:27 UTC](https://discourse.nodered.org/t/ur-robot-tcp-server/30424 "2020-07-21T13:27:08Z")

</div>

Hi, I am trying to set a TCP(server/client) connection between an UR robot and red-node but it seems that I don't know what I'm doing. The robot routine is fairly simple. It opens a socket (TCP client) and checks that …

---

## [Accessing flow context from the subflow](https://discourse.nodered.org/t/accessing-flow-context-from-the-subflow/30467)

<div class="topic-metadata">

**Author:** [@krzydec](https://discourse.nodered.org/u/krzydec)\
**Replies:** 8\
**Last updated:** [21 July 2020 12:39 UTC](https://discourse.nodered.org/t/accessing-flow-context-from-the-subflow/30467 "2020-07-21T12:39:44Z")

</div>

Hello I'm trying to package some of my flows into sub-flows to make it easier to follow. One of my function nodes is going through the flow context store using: flow.keys() and delete some variables when they are n…

---

## [Copying my Door control status back to my Mysql databse](https://discourse.nodered.org/t/copying-my-door-control-status-back-to-my-mysql-databse/30383)

<div class="topic-metadata">

**Author:** [@shipra](https://discourse.nodered.org/u/shipra)\
**Replies:** 95\
**Last updated:** [21 July 2020 12:38 UTC](https://discourse.nodered.org/t/copying-my-door-control-status-back-to-my-mysql-databse/30383 "2020-07-21T12:38:05Z")

</div>

I want to write and insert into a column (which is Door Status) ,it should be written as Door open /Door close back to mysql databse how to do that?Please help

---

## [Error - port not open - not reading CAN Hat from serial](https://discourse.nodered.org/t/error-port-not-open-not-reading-can-hat-from-serial/30468)

<div class="topic-metadata">

**Author:** [@edwardr](https://discourse.nodered.org/u/edwardr)\
**Replies:** 0\
**Last updated:** [21 July 2020 12:13 UTC](https://discourse.nodered.org/t/error-port-not-open-not-reading-can-hat-from-serial/30468 "2020-07-21T12:13:49Z")

</div>

I\`m trying to access the sensor data from /dev/ttys0 on my pi using a can hat rs485. The can hat - https://www.waveshare.com/w/upload/2/29/RS485-CAN-HAT-user-manuakl-en.pdf I\`ve installed the driver for the can hat but…

---

## [How to monitor Each node-red workflow execution time](https://discourse.nodered.org/t/how-to-monitor-each-node-red-workflow-execution-time/30455)

<div class="topic-metadata">

**Author:** [@venkat1497](https://discourse.nodered.org/u/venkat1497)\
**Replies:** 15\
**Last updated:** [21 July 2020 11:13 UTC](https://discourse.nodered.org/t/how-to-monitor-each-node-red-workflow-execution-time/30455 "2020-07-21T11:13:50Z")

</div>

I created multiple workflows in node-red window. Now i want know each workflow execution time and how can I monitor in runtime? Is it possible? If yes please let me know. Thanks.

---

## [Pi Shutdown Button with an OK/Cancel Notification](https://discourse.nodered.org/t/pi-shutdown-button-with-an-ok-cancel-notification/30459)

<div class="topic-metadata">

**Author:** [@oncdastan](https://discourse.nodered.org/u/oncdastan)\
**Replies:** 4\
**Last updated:** [21 July 2020 11:04 UTC](https://discourse.nodered.org/t/pi-shutdown-button-with-an-ok-cancel-notification/30459 "2020-07-21T11:04:35Z")

</div>

Hi. Here is my flow: \[{"id":"b699b242.275aa","type":"ui\_button","z":"4cdd06f6.faf528","name":"","group":"843bc78a.c5b078","order":5,"width":0,"height":0,"passthru":false,"label":"Shutdown","tooltip":"","color":"","bgcol…

---

## [Modbus / Temp Sensor and Rasp Pi through Node Red](https://discourse.nodered.org/t/modbus-temp-sensor-and-rasp-pi-through-node-red/30353)

<div class="topic-metadata">

**Author:** [@edwardr](https://discourse.nodered.org/u/edwardr)\
**Replies:** 21\
**Last updated:** [21 July 2020 10:37 UTC](https://discourse.nodered.org/t/modbus-temp-sensor-and-rasp-pi-through-node-red/30353 "2020-07-21T10:37:56Z")

</div>

Hi guys, I\`m having some real trouble trying to sort a project at the moment - I have the waveshare can hat connected to my pi hoping to read data from a Rs485 sht20 temp sensor. The can hat The sensor- http://w…

---

## [Node-red-contrib-msg-queue Data base](https://discourse.nodered.org/t/node-red-contrib-msg-queue-data-base/30431)

<div class="topic-metadata">

**Author:** [@develop5632](https://discourse.nodered.org/u/develop5632)\
**Replies:** 3\
**Last updated:** [21 July 2020 10:22 UTC](https://discourse.nodered.org/t/node-red-contrib-msg-queue-data-base/30431 "2020-07-21T10:22:21Z")

</div>

Hi everyone, if someone has used the node-red-contrib-msg-queue I have a doubt: The queue is stored in a SQLITE Database which is installed locally on the device that is running the Node Red. This node stores automatica…

[Previous page](https://discourse.nodered.org/c/general/7.md?page=708)

[Next page](https://discourse.nodered.org/c/general/7.md?page=710)