1 OVERVIEW
(9) Remote password check function
(Details are explained in the User's Manual (Application) and the Reference Manual.)
(a)The remote password check function of the Q series C24 prevents users at a remote location to access QCPUs illegally using the modem function of the
Q series C24.
(The remote password is checked in the following forms of data communication)
• Communication using the MC protocol
(The remote password check is not carried out in data communication using the non procedure/bidirectional protocols.)
• Access to the PLC through GX Developer
The remote password function is one of the QCPU functions and used for preventing illegal access to the QCPU by other users.
Use GX Developer to set a remote password for the QCPU in order to activate the remote password function of the QCPU.
(b)If the Q series C24 is specified in the parameters of a QCPU as being subject to the remote password check, the remote password can be unlocked (canceled) using either one of the methods below, to allow data
communication from the external device. It is necessary to connect a line to the modem first.
• When communicating using the MC protocol
Use the dedicated command for communication using the MC protocol to unlock the remote password from the external device.
• When accessing the PLC through GX Developer
Unlock the remote password using GX Developer at the start of online operation.
The remote password is automatically locked by disconnecting the line to the modem.
Set the parameters to make the Q series C24 as a subject to the remote password check.
QCPU
Remote 
password
GX Developer
| Accessing | |
| external device | |
Q series C24 | Dialup line | |
Remote | ||
Modem | ||
password | Modem | |
check |
| |
| Communication using the MC protocol | |
| Communication through GX Developer. |
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