Mitsubishi Electric MELSEC iQ-F Series User Manual page 47

■Procedure for clearing the DNS setting storage area
The following describes the procedure for clearing the DNS setting storage area.
1.
Write 1 to 'DNS setting storage area clear request' (Un\G4400).
2.
Check the write result with the following buffer memory areas.
Buffer memory address Name
Un\G4401.b0 DNS setting storage area clear completed
Un\G4401.b1 DNS setting storage area clear error
Un\G4404 DNS setting storage area clear error code
3.
When the clear processing is completed successfully, power off and on the system or reset the CPU module.
4.
Check that the DNS setting values configured with the module parameters are stored in the DNS server address areas
(Un\G4390 to Un\G4397).
If the clear processing for the DNS setting storage area is not completed successfully, the error code (1941H)
is stored in 'DNS setting storage area clear error code (Un\G4404).
Precautions
The following lists the precautions on the DNS setting change function.
■Power-off and CPU module reset
Do not power off the system or reset the CPU module while writing to or clearing the DNS setting storage area. Otherwise,
values may not be reflected to the DNS setting storage area.
Powering off the system or resetting the CPU module is not required after checking that 'DNS setting storage area write
completed' (Un\G4399.b0) and 'DNS setting storage area clear completed' (Un\G4401.b0) are turned on.
■DNS settings configured with the parameters
For the DNS settings of the Ethernet module, priority is given to the values in the DNS setting storage area over the values in
the module parameters.
Whether the DNS setting change function is enabled can be checked with 'DNS setting change function enable flag'
(Un\G4402).
To use the DNS settings configured with the module parameters, clear the DNS setting storage area.
■Execution timings of write processing and clear processing
When operating 'DNS setting storage area write request' (Un\G4398) or 'DNS setting storage area clear request' (Un\G4400)
in such a way as turning it on, off, and on or turning it off, on, and off at short intervals, the operation results and the values in
the operation result storage buffer memory may not match. Therefore, if operating a DNS setting storage area write request or
clear request at short intervals, check in advance that b0 of 'DNS setting area write completed' (Un\G4399) or b0 of 'DNS
setting area clear completed' (Un\G4401) has turned on.
If both 'DNS setting storage area write request' (Un\G4398) and 'DNS setting storage area clear request' (Un\G4400) are
turned off and on, the write processing or clear processing may not be executed.
■Failure of writing to or reading from the DNS setting storage area
If writing to or reading from the DNS setting storage area fails, the error code (1814H) is stored in the event history, and the
DNS settings configured with the module parameters are set to the Ethernet module.
When completed successfully
On
Off

When completed with an error
On
On
Error code
4 FUNCTION LIST
4.3 Other Functions
4
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