# Implementation error: Cannot get sub-task index for sample time \[0.002, 0\] in task '\[0, 0\]'

**URL:** <https://forum.plexim.com/t/implementation-error-cannot-get-sub-task-index-for-sample-time-0-002-0-in-task-0-0/878>\
**Category:** RT Box\
**Tags:** rt-box\
**Created:** [October 17, 2020, 9:55am UTC](https://forum.plexim.com/t/implementation-error-cannot-get-sub-task-index-for-sample-time-0-002-0-in-task-0-0/878 "2020-10-17T09:55:05Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![efrain\_ibaceta](https://avatars.discourse-cdn.com/v4/letter/e/6de8d8/32.png) [@efrain\_ibaceta](https://forum.plexim.com/u/efrain_ibaceta)\
**Post date:** [October 17, 2020, 9:55am UTC](https://forum.plexim.com/t/implementation-error-cannot-get-sub-task-index-for-sample-time-0-002-0-in-task-0-0/878/1 "2020-10-17T09:55:05Z")

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hello. I am using RT BOX 1 and when try to upload a model from PLECS stadnalone I get the following error:

“Implementation error: Cannot get sub-task index for sample time [0.002, 0] in task ‘[0, 0]’.”

why does it happen and any suggestion to solve it?

regards

[M3c-PSPWM - EFM\_LFM -baja escala - v4.plecs](https://forum.plexim.com/uploads/short-url/spCR8QUYGa3WYGzXACffBaMMRS0.plecs) (850 KB)

 ![implementation error.png](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/1X/d92edddc886495ed9fe5686c317695ac7b67e1bc.png)

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<div class="post-metadata">

**Author:** ![Bryan\_Lieblick](https://dub1.discourse-cdn.com/flex006/user_avatar/forum.plexim.com/bryan_lieblick/32/10_2.png) [@Bryan\_Lieblick](https://forum.plexim.com/u/Bryan_Lieblick)\
**Post date:** [October 21, 2020, 11:15am UTC](https://forum.plexim.com/t/implementation-error-cannot-get-sub-task-index-for-sample-time-0-002-0-in-task-0-0/878/2 "2020-10-21T11:15:00Z")

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The specific issue has to due with the ZOH blocks in your “modelo de clusteres” subsystem. If you remove these blocks or set the sample time to “Ts” then the issue goes away.

That being said, prior to running this model on the RT Box there are many fundamental changes required to your model. Some major changes are to 1) use the “Full Bridges (Series Connected)” power modules for your MMC power stage 2) use the “PWM Out” block and" PWM Capture" block for PWM generation and sensing.

Refer to the [RT Box tutorials](https://www.plexim.com/support/tutorials?body_value=All&field_tutorial_product_value=2)to get started, particularly the Real-Time Workflow section of the Introduction to the RT Box tutorial which outlines the steps to take a conventional PLECS model and modify it for real-time.