Mitsubishi Electric LCPU-U-HW Safety Manuallines page 4

[Design Precautions]
● For the operating status of each station after a communication failure, refer to
relevant manuals for the network. Failure to do so may result in an accident
due to an incorrect output or malfunction.
● When changing data of a running programmable controller from a peripheral
connected to the CPU module or from an external device such as a personal
computer connected to an intelligent function module, configure an interlock
circuit in the program to ensure that the entire system will always operate
safely.
For other controls to a running programmable controller (such as program
modification or operating status change), read relevant manuals carefully and
ensure the safety before the operation.
Especially, in the case of a control from an external device to a remote
programmable controller, immediate action cannot be taken for a problem on
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.
● An absolute position return by the CPU module's positioning function may turn
off the servo-on signal (servo off) for approximately 20ms, and the motor may
run unexpectedly. If this causes a problem, provide an electromagnetic brake
separately to lock the motor during absolute position return.
● Do not write any data to the "system area" or "write-protect area" (R) of the
buffer memory in an intelligent function module.
Also, do not turn on any "use prohibited" signal that is output from the CPU
module to the intelligent function module.
Doing so may cause malfunction of the programmable controller system.
● When setting auto refresh parameters, specify "Y" for the remote output RY
refresh devices. Specifying any other than "Y" (for example, M or L) will hold
the previous device status in the case of a CPU stop. For information on how
to stop the data link, refer to the MELSEC-L CC-Link System Master/Local
Module User's Manual.
● Disconnection of a communication cable (such as a CC-Link dedicated cable)
may make the line condition unstable, causing communication errors on
multiple stations on the network. Configure an interlock circuit in the program
so that the system will operate safely even if these communication errors
occur on multiple stations. Failure to do so may result in an accident due to an
incorrect output or malfunction.
WARNING
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