5DATA COMMUNICATION USING THE MELSEC COMMUNICATION PROTOCOL

MELSEC-Q

5.1.5 Support for the QCPU remote password function

This section explains an overview of the remote password function when a remote password is set for the Q series C24 mounted to a QCPU.

See Chapter 3 of the User's Manual (Application) for a detailed explanation.

(1) Checking remote passwords

If the following items are set to the QCPU using GX Developer, the Q series C24 performs a remote password check whenever an external device accesses the PLC using the modem function of the Q series C24.

(a)Setting by GX Developer

•When the remote password is set on the QCPU with the Q series C24.

•When the Q series C24 is set to be subject to the remote password check.

(b)Access in which the remote password is checked

The remote password is checked when the following access is attempted. Access attempts to all PLCs of the local station (the local station with the Q series C24 and other stations accessed via the local station) are subject to the remote password checking.

(Access function to the PLC in which the remote password is checked)

•Data communication using the MC protocol

•Access to the PLC using GX Developer

The remote password is not checked in data communication using the non procedure/bidirectional protocols.

(c) Remote password to be checked

The check is performed against the remote password set to the local station QCPU with the Q series C24.

Access to the specified station is allowed if the remote password specified by the user and the remote password set to the QCPU match when accessing.

(2)Data communication procedure

1)Initialize the modem.

2)Connect the line from the external device.

3)Unlock (cancel) the remote password of the QCPU belonging to the station with the Q series C24 mounted from the external device via the dedicated command for communication using the MC protocol.

4)Initiate the data communication between the external device and PLC using the MC protocol.

5)Disconnect the modem line from the external device side when completing the data communication using the MC protocol.

The remote password is automatically locked when the modem is disconnected.

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