* SETPASSWORD string
{* Applicable only to M+ PLC models}Purpose | When this statement is
executed, the PLC will not properly respond to any host link commands sent to it except
the command "PWxxxx
xx" which must contains the same string
"xxxx
xx" (not more than 19 characters) as defined in the SETPASSWORD
command. All other commands will receive a "PWER" response indicating a
"password error" state. Once the correct password has been accepted the PLC will
work as normal and respond to all host link commands. Execution of "PW" host
link command without any string will put the password lock back in force to prevent
unauthorized accessWhen
using TRiLOGI Version 4.1x or 5.x the editor will automatically prompt you to enter the
password string if it encounters a PLC which has been password-locked. Note that the
password is case sensitive. |
Examples | SETPASSWORD "I love TRiLOGI" |
Comments: | This feature is mainly used
to protect an unattended PLC which is linked to an auto-answer modem. Without password
protection anybody can dial in with a TL41.EXE and have full control of the PLC, which may
be a serious security problem. When TL41.EXE disconnects the modem it automatically
executes the "PW" command to re-arm the password lock so that there will not be
unauthorized access by subsequent callers. Within the PLC software you may also use a
timer to periodically re-arm the PLC with this command for maximum protection. You can
also use different passwords for different time of the day or a set of rotating passwords
to provide greater security. If you are linking the PLC to the internest via TRiLOGI Version 5.0, you will notice that the TLServer already provides username/password authentication. However, the password here works independent of the access provided via TLServer, hence this command can still be used to provide an additional layer of security against unauthorized access to the PLC. |