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[Design Precautions]
WARNING
● When the safety extension module detects a fault in an external power supply or itself, it turns off the
outputs. Configure an external circuit so that the connected devices are powered off according to the
output status (off) of the safety extension module. Incorrect configuration may result in an accident.
● Configure safety circuits external to a programmable controller to ensure that the entire system
operates safely even when a fault occurs in an external power supply or a programmable controller.
Failure to do so may result in an accident due to an incorrect output or malfunction.
(1) Emergency stop circuits, protection circuits, and protective interlock circuits for conflicting
operations (such as forward/reverse rotations or upper/lower limit positioning) must be configured
external to the programmable controller.
(2) Outputs may remain on or off due to the failure of components such as a relay, transistor, and a
triac in an output circuit. For output signals that may lead to serious accidents, external circuits
and mechanisms should be designed to ensure safe machinery operation in such a case.
● In an output circuit, when a load current exceeding a rated current or an over current caused by a load
short-circuit flows for a long time, it may cause smoke and fire. To prevent this, configure an external
safety circuit, such as a fuse.
● When changing data of a running programmable controller, configure an interlock circuit in the
program to ensure that the entire system will always operate safely.
For other forms of control (such as program modification, parameter change, forced output, or
operating status change) of a running programmable controller, read the relevant manuals carefully
and ensure that the operation is safe before proceeding.
Improper operation may damage machines or cause accidents.
● For safety relays, configure an external circuit using a device such as a fuse or breaker to protect a
short-circuit current.
● Create an interlock program using a reset button to prevent the safety extension module from
restarting automatically after the safety function is activated and the safety extension module turns off
the outputs.
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