Micro820 and Micro850 controllers Default IP Address

In this “Tech Files” installment, we look at a recent issue with trying to connect to a Micro820 right out the box.  Upon powering the Micro820 CPU straight from the box, the question became evident – how do I connect to this thing?  The Micro820 does not have a built-in USB port, and the default IP address is unknown.  Fortunately the solution is quite easy to work through.  The steps below come from Rockwell Automation’s Knowledge Base AID 546239.  This tech note is accessible to everyone (regardless of TechConnect status).  I tested the steps with my own Micro820 demo case, and the solution presented below worked with no issues.


The Solution

The out of box configuration for the Ethernet port is for DHCP (no BOOTP support). If a DHCP server doesn’t respond with an IP address within 15 seconds, then the controller will assign itself a random IP address (like a Windows PC). This allows someone to direct connect a PC Ethernet port to the Micro820 or 850 Ethernet port, browse for the Micro820 or Micro850 and connect using Connected Components Workbench.

To establish communications with a controller configured to use a random default address follow this procedure:

Note: Controller must be in PROG mode and you cannot be online to apply settings change.

  1. Shutdown Connected Components Workbench and RSLinx Classic software.
  2. Open Windows Ethernet card settings and set IP configuration to:IP =
    Subnet Mask =




  3. Open the RSLinx Classic software.
  4. Go to Communications –> Configure Drivers… .Image
  5. From Available Driver Types pull down list select EtherNet/IP Driver.

  6. Add new driver by selecting OK.Image
  7. Configure driver to browse your local subnet’s network card.Image
  8. Click Apply to the settings and then hit OK.
  9. Close the Configure Drivers window.
  10. Go to Communications –> RSWho.Image
  11. Expand the Ethernet/IP (AB_ETHIP-1) driver created before to allow the software to scan the subnet.Image
  12. Right click on controller and select Module Configuration.Image
  13. In Module Configuration, click on Port Configuration.
  14. Set the Network Configuration Type to Static.
  15. Set the IP settings and hit the Apply then the OK button when done.Image
  16. Change the PC’s IP settings to be on the same network as the new controller’s IP settings.

Additional Resources