# Usb port reading problem

**URL:** <https://discourse.nodered.org/t/usb-port-reading-problem/75836>\
**Category:** General\
**Tags:** function-node\
**Created:** [27 February 2023 21:38 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836 "2023-02-27T21:38:28Z")\
**Posts on this page:** 20\
**Page:** 1

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**Author:** ![RemyH](https://avatars.discourse-cdn.com/v4/letter/r/c67d28/32.png) [@RemyH](https://discourse.nodered.org/u/RemyH)\
**Post date:** [27 February 2023 21:38 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/1 "2023-02-27T21:38:28Z")

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Bonjour

I installed node-red on a debian 10 VM on proxmox 7

on using the serial port function and I have this problem  
serial port /dev/ttyUSB1 error: Error: Error: Permission denied, cannot open /dev/ttyUSB1"  
 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/4/e/4e3552416fca8fa0def5323b3dc518d60883211d.png)

param. VM proxmox  
 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/e/c/ec406da8d204a1f4764a1c071d59423e70112f72.png)

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<div class="post-metadata">

**Author:** ![TotallyInformation](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/totallyinformation/32/31_2.png) [@TotallyInformation](https://discourse.nodered.org/u/TotallyInformation)\
**Post date:** [27 February 2023 21:55 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/2 "2023-02-27T21:55:48Z")

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I don't know proxmox but I can tell you that most user accounts on Debian won't have access to serial/usb unless you add the right group to the account. `ls -la /dev/ttyUSB*` should let you see the right group you need to add.

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<div class="post-metadata">

**Author:** ![RemyH](https://avatars.discourse-cdn.com/v4/letter/r/c67d28/32.png) [@RemyH](https://discourse.nodered.org/u/RemyH)\
**Post date:** [28 February 2023 07:57 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/3 "2023-02-28T07:57:07Z")

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Salut

thank you for your reply  
I had already included it  
 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/7/b/7bab7351ebe33af2728f5fa6f8914a02adf5a4e8.png)

what can also say is that in the drop-down menu of the serial port,  
NR does not offer me the ports when I click on the magnifying glass

![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/5/6/5604a18351ffa5bccf2e7c19ddb5ea40499267e8.png)

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<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [28 February 2023 08:26 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/4 "2023-02-28T08:26:56Z")

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Are you sure which user is running node red?

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<div class="post-metadata">

**Author:** ![RemyH](https://avatars.discourse-cdn.com/v4/letter/r/c67d28/32.png) [@RemyH](https://discourse.nodered.org/u/RemyH)\
**Post date:** [28 February 2023 08:43 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/5 "2023-02-28T08:43:05Z")

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yes everything works except the serial ports

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<div class="post-metadata">

**Author:** ![TotallyInformation](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/totallyinformation/32/31_2.png) [@TotallyInformation](https://discourse.nodered.org/u/TotallyInformation)\
**Post date:** [28 February 2023 09:47 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/6 "2023-02-28T09:47:02Z")

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Can you share the startup script for Node-RED please? We need to confirm what user account is used to start Node-RED and then make sure that it is added to the `dialout` group.

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<div class="post-metadata">

**Author:** ![RemyH](https://avatars.discourse-cdn.com/v4/letter/r/c67d28/32.png) [@RemyH](https://discourse.nodered.org/u/RemyH)\
**Post date:** [28 February 2023 13:21 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/7 "2023-02-28T13:21:02Z")

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what is the name of the file

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<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [28 February 2023 13:48 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/8 "2023-02-28T13:48:56Z")

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How do you start node red?

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<div class="post-metadata">

**Author:** ![RemyH](https://avatars.discourse-cdn.com/v4/letter/r/c67d28/32.png) [@RemyH](https://discourse.nodered.org/u/RemyH)\
**Post date:** [28 February 2023 13:50 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/9 "2023-02-28T13:50:50Z")

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yes everything works except the serial ports

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<div class="post-metadata">

**Author:** ![bluescreentt](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/bluescreentt/32/52541_2.png) [@bluescreentt](https://discourse.nodered.org/u/bluescreentt)\
**Post date:** [28 February 2023 15:04 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/10 "2023-02-28T15:04:41Z")

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have you tried the complete id ? /dev/serial/by-id/xxxxxxxxxxxxx

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<div class="post-metadata">

**Author:** ![RemyH](https://avatars.discourse-cdn.com/v4/letter/r/c67d28/32.png) [@RemyH](https://discourse.nodered.org/u/RemyH)\
**Post date:** [28 February 2023 15:19 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/11 "2023-02-28T15:19:50Z")

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![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/0/0/00369c3b0dca6feb4672fff89e9ce671b16bb33c.png)

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<div class="post-metadata">

**Author:** ![TotallyInformation](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/totallyinformation/32/31_2.png) [@TotallyInformation](https://discourse.nodered.org/u/TotallyInformation)\
**Post date:** [28 February 2023 18:13 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/12 "2023-02-28T18:13:27Z")

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> [@RemyH](#):
>
> what is the name of the file

I don't know. It depends how you start Node-RED.

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<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [28 February 2023 18:30 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/13 "2023-02-28T18:30:06Z")

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> [@RemyH](#):
>
> yes everything works except the serial ports

That does not tell us what command you use to start node red, and from which directory you run it.

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<div class="post-metadata">

**Author:** ![RemyH](https://avatars.discourse-cdn.com/v4/letter/r/c67d28/32.png) [@RemyH](https://discourse.nodered.org/u/RemyH)\
**Post date:** [28 February 2023 18:59 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/14 "2023-02-28T18:59:27Z")

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I don't have this info  
you will have to help me  
do you want me to edit the node-red-service file?

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<div class="post-metadata">

**Author:** ![TotallyInformation](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/totallyinformation/32/31_2.png) [@TotallyInformation](https://discourse.nodered.org/u/TotallyInformation)\
**Post date:** [28 February 2023 19:30 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/15 "2023-02-28T19:30:30Z")

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> [@RemyH](#):
>
> do you want me to edit the node-red-service file?

If that's how you are starting node-red, you can just share it with us as long as there is nothing sensitive in it.

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<div class="post-metadata">

**Author:** ![RemyH](https://avatars.discourse-cdn.com/v4/letter/r/c67d28/32.png) [@RemyH](https://discourse.nodered.org/u/RemyH)\
**Post date:** [1 March 2023 08:53 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/16 "2023-03-01T08:53:12Z")

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see the nodered.service

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/b/b/bbe3b77b3fcf513be497d12555523126b07fe002.png)

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<div class="post-metadata">

**Author:** ![TotallyInformation](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/totallyinformation/32/31_2.png) [@TotallyInformation](https://discourse.nodered.org/u/TotallyInformation)\
**Post date:** [1 March 2023 09:43 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/17 "2023-03-01T09:43:42Z")

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Right, so now we know that you are starting Node-RED using a user id of `Jeedom`.

So can you please report the output of this command: `groups Jeedom`

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<div class="post-metadata">

**Author:** ![RemyH](https://avatars.discourse-cdn.com/v4/letter/r/c67d28/32.png) [@RemyH](https://discourse.nodered.org/u/RemyH)\
**Post date:** [1 March 2023 09:56 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/18 "2023-03-01T09:56:16Z")

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![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/f/5/f5c5c791479695af5c3d0ab7200539fe42d4034d.png)

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<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [1 March 2023 10:13 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/19 "2023-03-01T10:13:55Z")

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Can you post the output of  
`node-red-stop`  
`node-red-start`  
Please copy/paste text rather than screenshot. When pasting use the `</>` button at the top of the forum entry window and paste the text where it says.

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<div class="post-metadata">

**Author:** ![RemyH](https://avatars.discourse-cdn.com/v4/letter/r/c67d28/32.png) [@RemyH](https://discourse.nodered.org/u/RemyH)\
**Post date:** [1 March 2023 13:12 UTC](https://discourse.nodered.org/t/usb-port-reading-problem/75836/20 "2023-03-01T13:12:58Z")

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OK I copy/paste

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