<p>You only need the official LEGO MINDSTORMS EV3 software.</p>

<p>LEGO provides a "EV3 Block Developer Kit" on the MINDSTORMS <a href="https://www.lego.com/en-us/mindstorms/downloads" rel="noreferrer">downloads page</a>. This contains some minimal instructions on creating blocks. It also contains an older version of the EV3 software.</p>

<p>However, I have found that any version of the MINDSTORMS software can be used in "developer mode" by creating a file named <code>MindstormsEV3.ini</code> with the following contents:</p>

<pre><code>&lt;?xml version="1.0" encoding="utf-8" ?&gt; 
&lt;Tokens DeveloperMode="True" /&gt;
</code></pre>

<p>Save this file in the directory where the software is installed, e.g. <code>C:\Program Files (x86)\LEGO Software\LEGO MINDSTORMS EV3 Home Edition\</code>, then start the software.</p>

CC BY-SA 4.0
2018-07-06T10:32:20.363Z
This works. Drop a Block to a Program and double-click the block to inspect its .vix internals. Now you are in LabView edit mode.
leo
CC BY-SA 4.0
2018-07-06T10:35:08.790Z
When trying to save a .vix -- even a new Project and new .vix -- I get a "Unexpected error during save. Is the file read-only?". (Win7 SP1. file permission should not be the issue).
leo
CC BY-SA 4.0
2018-07-08T15:39:33.733Z
With a fresh copy of Lego Mindstorms Home Edition or Education, the error went away, but the save action is not saving the edited .vix back to disc. Any ideas?
leo
CC BY-SA 4.0
2018-07-08T19:15:15.613Z
Use *Export...* on the *Developer* menu to save the .vix file to disk.
David Lechner
CC BY-SA 3.0
2017-04-04T17:15:10.237Z
2017-04-04T17:15:10.237Z
David Lechner
<p>For input output you can use the OtherFiles Folder> EV3 and import the PBricks primitive.</p>

CC BY-SA 4.0
2018-12-14T17:28:09.617Z
2018-12-14T17:28:09.617Z
Jesse Born
<p>What do I need to create custom blocks and in particular the VIX part?</p>

CC BY-SA 3.0
2017-10-13T12:31:35.707Z
Would be great if someone could create a MQTT custom block.
Jan
<ev3><programming>
How can I create custom EV3 blocks (developer mode)?
Dimitrios Theotokis
# How can I create custom EV3 blocks (developer mode)?

(Asked by: username_0 on 2017-04-04)

What do I need to create custom blocks and in particular the VIX part?

**Tags:** ev3, programming

> **Comments:**
> **username_1**: Would be great if someone could create a MQTT custom block.  

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## 2 answers

### Answer by username_2 on 2017-04-04. Score: 6

You only need the official LEGO MINDSTORMS EV3 software.
LEGO provides a "EV3 Block Developer Kit" on the MINDSTORMS downloads page. This contains some minimal instructions on creating blocks. It also contains an older version of the EV3 software.
However, I have found that any version of the MINDSTORMS software can be used in "developer mode" by creating a file named MindstormsEV3.ini with the following contents:
 


Save this file in the directory where the software is installed, e.g. C:\Program Files (x86)\LEGO Software\LEGO MINDSTORMS EV3 Home Edition\, then start the software.

> **Comments:**
> **username_3**: This works. Drop a Block to a Program and double-click the block to inspect its .vix internals. Now you are in LabView edit mode.  
> **username_3**: When trying to save a .vix -- even a new Project and new .vix -- I get a "Unexpected error during save. Is the file read-only?". (Win7 SP1. file permission should not be the issue).  
> **username_3**: With a fresh copy of Lego Mindstorms Home Edition or Education, the error went away, but the save action is not saving the edited .vix back to disc. Any ideas?  
> **username_2**: Use *Export...* on the *Developer* menu to save the .vix file to disk.  

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### Answer by username_4 on 2018-12-14. Score: -2

For input output you can use the OtherFiles Folder> EV3 and import the PBricks primitive.


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