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PROGRAMMABLE SECURITY GUARD
If a modem answers the callback, the PSG will
proceed directly to SECONDARY PASSWORD
VALIDATION.
4.1.6 S
P
ECONDARY
ASSWORD
The unit will transmit "ENTER SECONDARY
PASSWORD" (if it is configured to transmit status
messages). The unit will now begin checking input
from the user against the secondary password. The
PSG will compare the string of received data
preceding a carriage return (maximum of 32
characters) to the programmed secondary
password. You have a (user-configured) limit to
enter the valid secondary password. If this limit is
exceeded the PSG will reenter Security Mode.
If a secondary password was received in error the
unit can optionally transmit a status message back
to the user ("invalid password"). The same retry
count is used for the secondary password as in the
primary password. Once the user meets this limit
the unit will reenter Security Mode after the
password timeout expires. If modem controls are
enabled, then DTR output will be dropped to
disconnect the call and the unit reenters Security
Mode.
If a valid password is received before the retry
count is met or the time period expires, then the
unit will transmit the status message, "secondary
password accepted, unit now in pass-thru mode"
(if it is configured to transmit status messages). The
PSG will then exit Security Mode and enter Pass-
Thru Mode.
4.1.7 E
R
NTERING OR
EENTERING
You can reenter Security Mode after any of the
following events:
• password retry limit is exceeded.
• password time limit is exceeded.
• Modem controls are enabled and a callback
attempt is unsuccessful.
• Modem controls are enabled and DCD input
goes inactive, indicating user-aborted
connection from a dialup modem.
• PSG receives the *@exit@* command when in
Pass-Thru Mode. NOTE: This command is case
sensistive: you must type in in lower case.
When you enter or reenter Security Mode, the PSG
will restart its retry count and stop the password
16
V
ALIDATION
S
M
ECURITY
ODE
timer until the PSG receives the next byte of data. If
modem controls are enabled, the unit will drop its
DTR output until DCD from the modem drops too.
The PSG will keep RTS output always active. The
PSG will monitor RI and DCD input and drive DTR
output unless you option the unit through DIP
switches for no modem controls.
In that case, the unit will not monitor RI and
DCD input and the PSG's DTR output will become
active on reset. DTR output will stay active unless
the unit is configured to run DTR/CTS flow
control. In that case, DTR output will drop when
the PSG's internal buffer is too full.
4.2 Pass-Thru Mode
In Pass-Thru Mode, the PSG will buffer and
retransmit all data received in each port out the
other port, using the word structure, baud rate,
and flow control configured for that port.
4.2.1 H
E
P
OW TO
NTER
Successfully negotiate the security barriers of either
port while in Security Mode.
4.2.2 H
E
P
OW TO
XIT
ASS
You can exit Pass-Thru Mode after any of the
following events:
• User disconnects call from remote modem
(if modem controls were enabled).
• Unit receives the Exit Pass-Thru Mode
command (*@exit@*). NOTE: This command
is case sensitive. You must type it in lower case
letters.
• The user-selectable "No Activity" timeout (30
seconds, 1 minute, 5 minutes, or 10 minutes)
expires.
4.3 Program Mode
Program Mode configures the unit with user-
supplied passwords and their associated parameters.
The parameters define the options associated with
each password.
Program Mode is menu-driven. To use Program
Mode you will need a dumb terminal or similar
device. No cursor positioning is used; the only
control characters used in the menu screens are
the carriage-return and linefeed characters that
terminate every line.
-T
M
ASS
HRU
ODE
-T
M
E
HRU
OD
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