Mitsubishi MELSEC Q Series Reference Manual page 360

3 - 300
3 WHEN COMMUNICATING USING THE QnA COMPATIBLE 3E/3C/4C FRAMES OR 4E FRAME
(b) Accessing via the C24 (the interface using the modem function is the object)
POINT
(1) When the C24 communicating data using the modem function is set as an
object of the remote password check, communication is enabled from after
the completion of the unlock process until the line is disconnected.
(2) All commands received while the remote password is in locked status will
generate an error response. Perform communication after executing the
remote password unlock process.
(3) The remote password lock process is automatically performed when the line is
disconnected.
3- 300