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[Design Precautions]
● Configure a circuit so that the external power supply is turned off first and then
the programmable controller.
If the programmable controller is turned off first, an accident may occur due to
an incorrect output or malfunction.
● 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 head module or from an external device such as a personal
computer connected to an intelligent function module, configure an interlock
circuit in the master station program to ensure that the entire system will
always operate safely.
For other controls to a running programmable controller (such as master
station 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 master station program, and determine
corrective actions to be taken between the external device and head module
in case of a communication failure.
● Do not write any data to the "system area" or "write-protect area" of the buffer
memory in an intelligent function module.
Also, do not turn on any "use prohibited" signal that is output from the head
module to the intelligent function module.
Doing so may cause malfunction of the programmable controller system.
● 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
3
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