Mitsubishi Electric MELSEC iQ-R Series User Manual page 5

[Design Precautions]
WARNING
● Especially, when a remote programmable controller is controlled by an external device, immediate
action cannot be taken if a problem occurs in the programmable controller due to a communication
failure. To prevent this, configure an interlock circuit in the program, and determine corrective actions
to be taken between the external device and CPU module in case of a communication failure.
● Do not write any data to the "system area" and "write-protect area" of the buffer memory in the
module. Also, do not use any "use prohibited" signals as an output signal from the CPU module to
each module. Doing so may cause malfunction of the programmable controller system. For the
"system area", "write-protect area", and the "use prohibited" signals, refer to the user's manual for the
module used. For areas used for safety communications, they are protected from being written by
users, and thus safety communications failure caused by data writing does not occur.
● If a communication cable is disconnected, the network may be unstable, resulting in a communication
failure of multiple stations. Configure an interlock circuit in the program to ensure that the entire
system will always operate safely even if communications fail. Incorrect output or malfunction due to a
communication failure may result in an accident. When safety communications are used, an interlock
by the safety station interlock function protects the system from an incorrect output or malfunction.
● If data exchanges of a PROFINET IO device module are disabled, the module sends input data (0) to
a PROFINET IO controller module. The PROFINET IO device module holds output data (at the time
when the data exchanges stopped) received from the PROFINET IO controller module in 'IO data
receive area' (Un\G0 to Un\G511) of the buffer memory.
Configure an interlock circuit (with 'IO data exchanging' (X1) and 'IO data receive error' (X2)) in the
program to ensure that the entire system will always operate safely even if communications fail.
[Security Precautions]
WARNING
● To maintain the security (confidentiality, integrity, and availability) of the programmable controller and
the system against unauthorized access, denial-of-service (DoS) attacks, computer viruses, and other
cyberattacks from external devices via the network, take appropriate measures such as firewalls,
virtual private networks (VPNs), and antivirus solutions.
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