# Can I detect when the ethernet shield is connected?

**URL:** <https://community.sparkfun.com/t/can-i-detect-when-the-ethernet-shield-is-connected/22280>\
**Category:** Arduino\
**Created:** [October 18, 2011, 2:43pm UTC](https://community.sparkfun.com/t/can-i-detect-when-the-ethernet-shield-is-connected/22280 "2011-10-18T14:43:05Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![justmark](https://avatars.discourse-cdn.com/v4/letter/j/a87d85/32.png) [@justmark](https://community.sparkfun.com/u/justmark)\
**Post date:** [October 18, 2011, 2:43pm UTC](https://community.sparkfun.com/t/can-i-detect-when-the-ethernet-shield-is-connected/22280/1 "2011-10-18T14:43:05Z")

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Is there a way to determine that the ethernet shield is connected to the arduino ? I’m working on an application that can have different communications options connected (xbee, ethernet, cellular), and detecting ethernet would be helpful.

Any thoughts?

Thanks.

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**Author:** ![Hardwareguy](https://avatars.discourse-cdn.com/v4/letter/h/7ba0ec/32.png) [@Hardwareguy](https://community.sparkfun.com/u/Hardwareguy)\
**Post date:** [October 19, 2011, 6:41pm UTC](https://community.sparkfun.com/t/can-i-detect-when-the-ethernet-shield-is-connected/22280/2 "2011-10-19T18:41:01Z")

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The shield should carry no current. Shield wires are usually only connected at one side of the point to point devices. I can’t imagine how the arduino board could do something that other products would have a tough time doing. There might be some capacitive way to do that with special circuitry. Those are my thoughts.

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**Author:** ![Mee\_n\_Mac](https://avatars.discourse-cdn.com/v4/letter/m/aeb1de/32.png) [@Mee\_n\_Mac](https://community.sparkfun.com/u/Mee_n_Mac)\
**Post date:** [October 20, 2011, 2:46am UTC](https://community.sparkfun.com/t/can-i-detect-when-the-ethernet-shield-is-connected/22280/3 "2011-10-20T02:46:29Z")

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> Hardwareguy:  
> The shield should carry no current. Shield wires are usually only connected at one side of the point to point devices. I can’t imagine how the arduino board could do something that other products would have a tough time doing. There might be some capacitive way to do that with special circuitry. Those are my thoughts.

I believe the OP was refering to one of these …

[http://www.arduino.cc/en/Main/ArduinoShields](http://www.arduino.cc/en/Main/ArduinoShields)

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**Author:** ![esklar81](https://avatars.discourse-cdn.com/v4/letter/e/aca169/32.png) [@esklar81](https://community.sparkfun.com/u/esklar81)\
**Post date:** [October 20, 2011, 2:47am UTC](https://community.sparkfun.com/t/can-i-detect-when-the-ethernet-shield-is-connected/22280/4 "2011-10-20T02:47:07Z")

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Hardwareguy,

Well, you certainly live up to your name! 😉

I believe that, by “ethernet shield”, the OP meant [[one of these](http://www.sparkfun.com/products/9026).

Eric]([Arduino Ethernet Shield - DEV-09026 - SparkFun Electronics](http://www.sparkfun.com/products/9026))