FP Modem-EU Technical Manual
3.6 Password Protection and Call Back Function
3.6 Password Protection and Call Back Function
Password protection for technical facilities (e.g. that are connected to the public telephone
network for telemaintenance) should definitely be activated in order to prevent malicious or
unintended calls.
Two security levels are possible:
Level 1
Access only with the correct password
Level 2
Access only with the correct password and the call back of the number
that was stored with &Z0.
Command Function
AT*P=xxxx<CR>
Entering the password. You can enter up to 7 characters. These
characters may contain letters and numbers and even _-$*+#:;&/\() .
Lower case letters are transformed into upper case letters when they are
entered!
AT*P?
AT*L
Displaying the password.
AT*P=
Deleting the password.
AT%S2
Activating password protection.
AT%S0
Deactivating password protection (default).
AT%S1
Activating password protection with security level 2. For this you have to
store a call back number x that contains up to 30 digits with AT&Z0=x in
the short-code dialing memory.
AT&Z0=x
Storing a call back number x in the short-code dialing memory with
register number 0.
For the modem that is protected by a password, register S0 should be at least set to 1 to enable
the modem to answer the incoming call automatically. After that a normal connection is actually
established, but the caller (the calling PLC) is asked to enter a password with the prompt:
"ENTER PASSWORD:" Every character entered is confirmed by an *. If the password was
entered correctly, the modem switches to data mode. Otherwise the prompt is repeated 3 times.
If the input is wrong or not carried out the connection is aborted.
After entering the correct password the connection is established. If the call back function is
enabled (AT%S1) the connection is aborted immediately and the distant modem (AT&Z0
register for the distant telephone number) is called up to finally establish the connection.
After successful comparison of the modulation procedure (handshaking), the modem
immediately switches to data mode and communication is possible.
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