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Hey everyone,
I’m currently working with MATLAB R2025b and using the MQTT blocks from the Industrial Communication Toolbox inside Simulink. I’ve run into an issue that’s driving me a bit crazy, and I’m not sure if it’s a bug or if I’m missing something obvious.
Here’s what’s happening:
  • I open the MQTT Configure block.
  • I fill out all the required fields — Broker address, Port, Client ID, Username, and Password.
  • When I click Test Connection, it says “Connection established successfully.” So far so good.
  • Then I click Apply, close the dialog, set the topic name, and try to run the simulation.
  • At this point, I get the following error:Caused by: Invalid value for 'ClientID', 'Username' or 'Password'.
  • When I reopen the MQTT config block, I notice that the Password field is empty again — even though I definitely entered it before and the connection test worked earlier.
It seems like Simulink is somehow not saving the password after hitting Apply, which leads to the authentication error during simulation.
Has anyone else faced this? Is this a bug in R2025b, or do I need to configure something differently to make the password persist?
Would really appreciate any insights, workarounds, or confirmations from anyone who has used MQTT in Simulink recently.
Thanks in advance!
Arkadiy Turevskiy
Arkadiy Turevskiy
Last activity on 15 Oct 2025 at 16:08

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Arkadiy
Hello Everyone, I’m Vikram Kumar Singh, and I’m excited to be part of this amazing MATLAB community!
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Pavan Kumar
Pavan Kumar
Last activity on 10 Oct 2025 at 13:00

Excited to link and sync to be a part of better learning experience
Patrick
Patrick
Last activity about 19 hours ago

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Last activity on 9 Oct 2025 at 20:48

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Benjamin
Benjamin
Last activity on 2 Oct 2025 at 17:03

excited to learn more on Mathworks
Nermin
Nermin
Last activity on 2 Oct 2025 at 15:23

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Dyuman Joshi
Dyuman Joshi
Last activity on 30 Sep 2025 at 10:02

For some time now, this has been bugging me - so I thought to gather some more feedback/information/opinions on this.
What would you classify Recursion? As a loop or as a vectorized section of code?
For context, this query occured to me while creating Cody problems involving strict (so to speak) vectorization - (Everyone is more than welcome to check my recent Cody questions).
To make problems interesting and/or difficult, I (and other posters) ban functions and functionalities - such as for loops, while loops, if-else statements, arrayfun() and the rest of the fun() family functions. However, some of the solutions including the reference solution I came up with for my latest problem, contained recursion.
I am rather divided on how to categorize it. What do you think?
Harel
Harel
Last activity on 25 Aug 2025

Hi,
I have some problem, I want to upload my data that sample rate at 500HZ, every sevral seconds.
My data include 12 bytes, and it measure 500HZ, for example for 15 seconds I coolect 15*500*12 = 84KB.
Can I upload this data to ThingSpeak? It is possible to use with Free acount (I am student and this is my project)
How can help me..
Hey cody fellows :-) !
I recently created two problem groups, but as you can see I struggle to set their cover images :
What is weird given :
  • I already did it successfully twice in the past for my previous groups ;
  • If you take one problem specifically, Problem 60984. Mesh the icosahedron for instance, you can normally see the icon of the cover image in the top right hand corner, can't you ?
  • I always manage to set cover images to my contributions (mostly in the filexchange).
I already tried several image formats, included .png 4/3 ratio, but still the cover images don't set.
Could you please help me to correctly set my cover images ?
Thank you.
Nicolas
Is there a hardware support package available for the MP series?
I'm facing an issue where my Thinkspeak graph is not displaying, even though I'm using exactly the same code as my friend. The code works perfectly in their Thinkspeak account, but not on mine. I've checked the API keys, channel settings, and data formats, but everything seems similar. Has anyone else faced this problem, or do you have tips on what to check next? Suggestions are welcome!
Hi!
I'm having trouble sending data to a channel using MQTT. I'm using a program that was working perfectly until just a few days ago, but after making some minor changes yesterday, it stopped working. I’ve also tested it manually using the MQTTX client. If I send data using CURL and GET, it works fine.
It’s a bit strange...
Thankfully,
Ernesto.
Is it possible to create a Simulink model that is independent of specific microcontrollers?
For example, in the model, the STM32 block is used for CAN transmission. But if I want to deploy the same model to an Arduino, I have to replace the STM32 block with an Arduino-compatible one.
So, is it possible to create a custom block or abstraction that works across multiple microcontrollers like STM32, PIC32, and Arduino without changing the hardware-specific block each time?