Schneider Electric Modicon BM85 - Manual (Page 61)

Configuring the Modbus Models 890 USE 103 00 51
3.10.2 Using the V4 Screen
To write (save) the configuration you have entered into the BM85, enter
the following command:
W
To initialize the entire set of configuration parameters in the BM85 to
their default values, enter the following command:
D
Note that initializing the configuration parameters also clears the
Modbus Address Map tables for all four ports to zeros.