28  FUNCTIONS
 
437
28
Functions different 
(modified or 
restricted) from 
those of the process 
mode
Remote operation Using a contact When the backup mode setting is enabled in the CPU 
parameter, both systems may be recognized as being 
mismatched in the system consistency check even if the 
remote operation is simultaneously performed on the systems 
because their operating statuses are mismatched depending 
on the timing.
Using an 
engineering tool
In a redundant system, the operation target of remote 
operations depends on the operation mode and type.
Page 491 Remote 
Operation
Boot operation Use the boot operation only to simultaneously start up both 
systems. When one system is restarted and the boot 
operation is used, an error occurs.
Page 493 Boot 
Operation
External input/output forced on/off function Forced on/off is reflected to the input/output devices of both 
systems and external outputs by registering or canceling 
forced on/off for the control system. (Forced on/off is reflected 
to both systems without setting tracking transfer setting in the 
CPU parameter.)
Page 494 External Input/
Output Forced On/Off 
Function
Test function Changes in values of devices and labels are transferred 
(tracking) from the control system to the standby system 
before the END processing. If the systems are switched 
between the change and the tracking transfer, the change is 
not reflected on the new control system.
Data logging function In a redundant system, the data logging function collects data 
only in the control system regardless of the operation mode.
Page 498 Data Logging 
Function
Multiple CPU system function This function cannot be used in redundant mode. 
Security function The security key setting is written or deleted on both systems 
individually, regardless of the operation mode.
Latch function When the systems are switched, the new control system and 
the new standby system start the value in "Interval Setting at 
Time Setting" in "Device Latch Interval Setting" from 0.
Label access setting from external device In the transfer setup of external devices that communicate 
with the CPU module through GOT, SLMP, or other methods, 
select "Control System/Standby System", "System A/System 
B", or "Not Specified" to start a communication with a global 
label name specified.
Program restoration information write 
selection
Only when the firmware versions of the CPU modules of both 
systems support the program restoration information write 
selection, "Not to Write" can be selected.
Page 1008 Added and 
Enhanced Functions
SFC function This function cannot be used in redundant mode. 
SLMP communication • There are notes for system switching when the system IP 
address matching function is not used.
• If a remote operation command is executed, the CPU 
modules enter different operating statuses and thus 
systems cannot be switched.
• For SLMP communications via the built-in Ethernet port of 
the CPU module, when communications are performed to 
the other system that cannot respond (power-off, reset, or 
tracking cable disconnection), a timeout error may occur.
• The SLMP frame send instruction (SP.SLMPSND) performs 
communications using IP addresses of the system A and B.
Page 501 SLMP 
Communication
Ethernet function File transfer 
function (FTP client)
• This function performs communications using IP addresses 
of the system A and B.
MELSEC iQ-R Ethernet 
User's Manual 
(Application)
Inter-module synchronization function This function cannot be used in redundant mode. 
Function Description Reference