BlockIO output set to zero when multiple blocks are used

There seems to be simulatin issues when using multiple Blocks form IO Device Builder app. Some outputs seem to always be zero in some cases.

I could narrow down the error a little bit but as far as I know the error occurs:

• when using multiple blocks (of one or different sensors)
• on blocks that have more than one output
• on the outputs that are the furthest down (lower right corner) on the block regardless on when the output is changed in the code
• delay() in the code does not fix the issue
• other code blocks that are executed in between the BlockIO dont fix the issue
• Commenting out the other blocks and just simulating one BlockIO individually fixes the issue
• Using one Output per Block fixes the issue.

Is there something I am doing wrong? I would like to avoid having to create 6 blocks just to read IMU data.

[Alex]

I am finding I have a similar problem. I made a Device IO block to read CAN messages over SPI without the interrupt (the built-in blocks all use the interrupt)and another to write to a DAC via I2C.

All of my read data from all of the output ports of my CAN read block work, but only the first DAC write works (it’s a 4 channel DAC, I am writing to the first 2). I haven’t tried making multiple DAC writes - are you duplicating the setup functions for multiple instances of your sensor reads?

Just wanted to share that this is not just a one-off.

Answer 1

[MULI]

Hi @Aaron Troll,

I understand you are facing issues with Simulink blocks generated by the IO Device Builder app, where multiple blocks or outputs result in some signals being stuck at zero. This could be due to:

• Simulink executes blocks sequentially, and incorrect order can cause outputs to remain zero.
• Multiple blocks with multi-output sensors might interfere with each other if not properly synchronized.

You can try the following approach to resolve this issue:

• Splitting outputs into individual blocks avoids conflicts and combine outputs later using “Mux” or “Bus Creator” blocks. You can refer to below documentation links for more information and examples related to these block: https://www.mathworks.com/help/releases/R2024a/simulink/slref/mux.html https://www.mathworks.com/help/releases/R2024a/simulink/slref/buscreator.html
• Enable Display > Blocks and Signals > Sorted Execution Order to check execution order.
• You can fix incorrect order using “Unit Delay” block to manage dependencies. You can refer to below links for more information on this block: https://www.mathworks.com/help/releases/R2024a/simulink/slref/unitdelay.html

By following these steps, you can resolve the issue effectively.