Ethernet Communication Module IFD9506 4. Open the setup page again, and IFD9506 is now locked by the password. You cannot open any of the settings now. To unlock the password, check “Unlock” and enter your original password. 10.2 Password Loss (Returning to Default Settings by RS-232) DVP-PLC Application Manual 39 Application Returning to default settings by RS-232. Steps (1) Set up password in IFD9506. (2) Supposed the password is forgotten, return to default settings through RS-232.