---
title: What is normally open (NO)?
description: NO
---

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# What is normally open (NO)?

## NO

NO = normally open, normally is disconnected, the coil without electric power disconnected.  
The sensor turns "on" when an object is detected.

 

![图一-4](https://kb.innovatingautomation.asia/hs-fs/hubfs/Knowledge%20Base/Simplified%20Chinese/Image/%E9%98%B2%E7%88%86%E7%94%B5%E6%84%9F%E5%BC%8F%E4%BC%A0%E6%84%9F%E5%99%A8/%E5%9B%BE%E4%B8%80-4.png?width=524&name=%E5%9B%BE%E4%B8%80-4.png)

This principle is the most commonly used in automation technology. 

 

![图二](https://kb.innovatingautomation.asia/hs-fs/hubfs/Knowledge%20Base/Simplified%20Chinese/Image/%E9%98%B2%E7%88%86%E7%94%B5%E6%84%9F%E5%BC%8F%E4%BC%A0%E6%84%9F%E5%99%A8/%E5%9B%BE%E4%BA%8C.png?width=435&name=%E5%9B%BE%E4%BA%8C.png)

[Learn more about Balluff's "normally open"-status](https://www.balluff.com.cn/en/cn/service/basics-of-automation/fundamentals-of-automation/electrical-wiring-of-sensors/)

 

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