Mitsubishi Electric MELSEC iQ-R Series User Manual page 5

[Design Precautions]
WARNING
● 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.
● To maintain the safety of the programmable controller system against unauthorized access from
external devices via the network, take appropriate measures. To maintain the safety against
unauthorized access via the Internet, take measures such as installing a firewall.
● Analog outputs may remain on due to a failure of the module. Configure an external interlock circuit
for output signals that could cause a serious accident.
[Design Precautions]
CAUTION
● Do not install the control lines or communication cables together with the main circuit lines or power
cables. Keep a distance of 100mm or more between them. Failure to do so may result in malfunction
due to noise.
● During control of an inductive load such as a lamp, heater, or solenoid valve, a large current
(approximately ten times greater than normal) may flow when the output is turned from off to on.
Therefore, use a module that has a sufficient current rating.
● After the CPU module is powered on or is reset, the time taken to enter the RUN status varies
depending on the system configuration, parameter settings, and/or program size. Design circuits so
that the entire system will always operate safely, regardless of the time.
● Do not power off the programmable controller or reset the CPU module while the setting values in the
buffer memory are being written to the flash ROM in the module. Doing so will make the data in the
flash ROM undefined. The values need to be set in the buffer memory and written to the flash ROM
again. Doing so also can cause malfunction or failure of the module.
● When changing the operating status of the CPU module (such as remote RUN/STOP) from the
external device, select "Do Not OPEN in Program" for the "Open Method Setting" in the module
parameter. The communication line will be closed when "OPEN in Program" is selected and the
remote STOP is executed from the external device. Consequently, the CPU module cannot reopen
the communication line, and the external device cannot execute the remote RUN.
● Power on or off the external power supply while the programmable controller is on. Failure to do so
may result in incorrect output or malfunction.
● At on/off of the power or external power supply, or at the output range switching, a voltage may occur
or a current may flow between output terminals for a moment. In this case, start the control after
analog outputs become stable.
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