# How to Connect to a PLC with an Unknown IP Address

**URL:** <https://community.br-automation.com/t/how-to-connect-to-a-plc-with-an-unknown-ip-address/285>\
**Category:** How-To & Wikis\
**Tags:** plc\
**Created:** [October 9, 2023, 8:19pm UTC](https://community.br-automation.com/t/how-to-connect-to-a-plc-with-an-unknown-ip-address/285 "2023-10-09T20:19:53Z")\
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**Author:** ![blake.eby](https://avatars.discourse-cdn.com/v4/letter/b/FF8800/32.png) [@blake.eby](https://community.br-automation.com/u/blake.eby)\
**Post date:** [October 9, 2023, 8:19pm UTC](https://community.br-automation.com/t/how-to-connect-to-a-plc-with-an-unknown-ip-address/285/1 "2023-10-09T20:19:53Z")

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Hi everyone! I’ve been asked this question a few times, so I figured I’d put it here.

NOTE: This is really only useful if you are using a controller without a C-FAST card. If you have an external card, just write your new project–known IP Address and all–via an Offline Installation.

Imagine you get your hands on a Compact-S or C-Panel PLC. You turn it on, eager to transfer the project you’ve been working on. You plug in your Ethernet cable, open up Automation Studio, try to search for it…and nothing shows up. Whoever used it last must have deactivated SNMP, and you don’t know the IP Address!

Fortunately, there’s a way to make your PLC discoverable again: put it into BOOT mode.

Typically, a PLC can be manually put into BOOT mode by pressing its reset button for less than 2 seconds, releasing it for less than 2 seconds, then pressing it holding it down again until the PLC enters BOOT mode. What BOOT mode looks like varies between different PLC families, so check your device’s data sheet to be sure.

1. Once in BOOT mode, make sure the desired ethernet port on your computer is connected to the ETHERNET port on the Controller via an ethernet cable.

2. In Automation Studio, go to Online → Settings…  

3. Make sure the “Browse” button is toggled ON  

4. You should see your PLC populate in the window, without an IP address set

5. Right-click your PLC and select “Set IP Parameters”  

6. If you have IP parameters set up in your open project, you can click “Copy from project” to set them; or you can enter the desired IP address for the Controller manually.  

7. Click OK to close the Parameters dialog box.

8. With the IP address set, right-click on your Controller and click “Connect”.  

9. In Automation Studio, you should see the current mode change from OFFLINE to something else in the bottom right corner or the screen, indicating that you are now connected.  

Now you can transfer your project. Keep in mind that your project’s ethernet settings will overwrite whatever IP address you just set.

Happy automating! 🤖

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