The PNP sensor:- This is a sensor who...

最新推荐文章于 2025-08-16 17:02:07 发布

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最新推荐文章于 2025-08-16 17:02:07 发布

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原文链接：https://my.oschina.net/panzerwl/blog/14138

本文详细介绍了PNP与NPN传感器的工作原理及其应用场景。PNP传感器在检测到金属目标时将输出拉高至正电源，适用于负载连接在地与输出间；而NPN传感器则将输出拉低至负电源，适用于负载连接在正电源与输出间。此外，文章还讨论了两种传感器在短路情况下的表现及与PLC输入设备的配合使用。

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The PNP sensor:- This is a sensor whose output pulls up to the positive supply rail when it senses a metal target. Thus any attached load to the sensor output must be connected between zero volts & the output of the sensor to operate.
This type of sensor is very vulnerable to short circuits to earth ( zero volts), a common fault if the wiring chafes/ becomes damaged. Often it will fry under this type of fault.

NPN sensor :- This is a sensor whose output pulls down to the negative ( 0 volts) supply rail when it senses a metal target. Thus any attached load to the sensor output must be connected between the Positive supply rail & the output of the sensor to operate. This type of sensor cannot survive a short up to the positive supply rail ( a very rare occurrence!). Shorts to the negative rail (zero volts) will not damage it at all & it can tolerate this indefinately.

Other factors affecting choice :- If there is a PLC attached then :-

a/ If the input device of the PLC registers a logic high/true state when left open circuit then this type of input is best served by an NPN sensor. This will pull the PLC input low when a target is sensed.

b/ If the input device of the PLC registers a logic low/false state when left open circuit, then this type of input is best served by a PNP sensor. This will pull the PLC input high when a target is sensed.

转载于:https://my.oschina.net/panzerwl/blog/14138