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Safety Precautions
During Power Supply
Do not touch any of the terminals or terminal blocks while the power is being
supplied. Doing so may result in electric shock.
Do not attempt to take any Unit apart. In particular, high-voltage parts are
present in the Power Supply Unit while power is supplied or immediately
after power is turned OFF. Touching any of these parts may result 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 abnormality occurs due to malfunction of the CPU Unit, 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 Controller outputs may remain ON or OFF due to deposition or burning
of the output relays or destruction of the output transistors. As a countermea-
sure for such problems, external safety measures must be provided to
ensure safe operation of the system.
The CPU Unit will turn OFF all outputs from Basic Output Units in the follow-
ing cases. The remote I/O slaves will operate according to the settings in the
slaves.
• If an error occurs in the power supply
• If the power supply connection becomes faulty
• If a CPU watchdog timer error or CPU reset occurs
• If a major fault level Controller error 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.
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 inputs. Provide external safety measures in controls
with monitoring of external power supply voltage as required so that the sys-
tem operates safely in such a case.
18
WARNING
CJ-series High-speed Counter Units Operation Manual for NJ-series CPU Unit(W492)
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