# How create Subnode URCAP

**URL:** <https://forum.universal-robots.com/t/how-create-subnode-urcap/41441>\
**Category:** Java\
**Created:** [October 9, 2025, 5:24pm UTC](https://forum.universal-robots.com/t/how-create-subnode-urcap/41441 "2025-10-09T17:24:49Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![eric.feldmann](https://avatars.discourse-cdn.com/v4/letter/e/94ad74/32.png) [@eric.feldmann](https://forum.universal-robots.com/u/eric.feldmann)\
**Post date:** [October 9, 2025, 8:06pm UTC](https://forum.universal-robots.com/t/how-create-subnode-urcap/41441/2 "2025-10-09T20:06:07Z")

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If I’m reading your stack trace right, it looks like it’s actually failing on addAproximacaoSubNode() (line 138) which would seem like it’s failing on

```auto
thisNode.addChild(aproxNode);

```

I would print the result of aproxNode just before that call and see if it’s coming back null or not. Regardless, I see what you’re trying to do and I don’t think it works that way. You have to implement a custom API interface to manipulate data in other nodes: [URCap Sample: URCap CustomAPI](https://forum.universal-robots.com/t/urcap-sample-urcap-customapi/3022)

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