Here's how to do this from a Windows PC on the same network as the CORIO unit:

1. Click START, 'Run' and enter 'CMD' to open an MS-DOS window.
2. Ping the CORIO unit from the PC by entering 'PING 10.1.2.123' or whatever IP address is valid.
3. Then run the 'ARP -A' command (address resolution protocol) and it will show a list of all IP addresses that the computer has contacted, along with the associated physical (MAC) addresses.
4. From the table it should be easy to see the MAC address.