Warnings
During Power Supply
Do not touch the terminal section while power is ON.
Electric shock may occur.
Do not attempt to take any Unit apart.
In particular, high-voltage parts are present in Units that supply power while power is
supplied or immediately after power is turned OFF
. Touching any of these parts may re-
sult in electric shock. There are sharp parts inside the Unit that may cause injury.
Fail-safe Measures
Provide safety measures in external circuits to ensure safety in the system if an abnor-
mality occurs due to malfunction of the CPU Unit, Industrial PC, other Units, or slaves or
due to other external factors affecting operation.
Not doing so may result in serious accidents due to incorrect operation.
Emergency stop circuits, interlock circuits, limit circuits, and similar safety measures
must be provided in external control circuits.
The CPU Unit or Industrial PC will turn OFF all outputs from Output Units in the following
cases. The remote I/O slaves will operate according to the settings in the slaves.
•
If a power supply error occurs.
•
If the power supply connection becomes faulty.
• If a CPU watchdog timer error or CPU reset occurs.
• If a Controller error in the major fault level occurs.
• While the CPU Unit is on standby until RUN mode is entered after the power is turned
ON
External safety measures must be provided to ensure safe operation of the system in
such cases.
The outputs may remain ON or OFF due to deposition or burning of the output relays or
destruction of the output transistors. As a countermeasure for such problems, external
safety measures must be provided to ensure safe operation of the system.
If external power supplies for slaves or other devices are overloaded or short-circuited,
the voltage will drop, outputs will turn OFF, and the system may be unable to read in-
puts. Provide external safety measures in control with monitoring of external power sup-
ply voltage as required so that the system operates safely in such a case.
You must take fail-safe measures to ensure safety in the event of incorrect, missing, or
abnormal signals caused by broken signal lines, momentary power interruptions, or oth-
er causes.
Not doing so may result in serious accidents due to incorrect operation.
Safety Precautions
17
NX-series System Units User's Manual (W523)
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