How do I know what the default IP address is for a Twido controller?

The default IP address is 85.16.x.y, where x.y is derived from the last two octets of the MAC address converted to decimal.
Example:
If the MAC address is 00.80.F4.81.45.22, the last two octets is 45.22. These must be converted to decimal. 45hex = 69dec and 22hex = 34dec.
Therefore, the default IP address would be 85.16.69.34