Cautions - Omron NX Series User Manual

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 abnor-
mality occurs due to malfunction of the CPU Unit, slaves, or Units or due to other ex-
ternal 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 out-
put relays or destruction of the output transistors. As a countermeasure for such prob-
lems, external safety measures must be provided to ensure safe operation of the sys-
tem.
The CPU Unit will turn OFF all outputs from Digital Output Units in the following cases.
The slaves will operate according to the settings in the slaves.
• If an error occurs in the power supply
• If a CPU 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
• If a system initialization error occurs
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 in-
puts. Provide external safety measures in controls with monitoring of external power
supply voltage as required so that the system operates safely in such a case.
Unintended outputs may be performed when an error occurs in variable memory or
memory for CJ-series Units. As a countermeasure for such problems, external safety
measures must be provided to ensure safe operation of the system.
Provide measures in the communications system and user program to ensure safety in
the overall system even if errors or malfunctions occur in data link communications or
remote I/O communications.
If there is interference in remote I/O communications or if a major fault level error oc-
curs, output status will depend on the products that are used.
Confirm the operation that will occur when there is interference in communications or a
major fault level error, and implement safety measures.
Correctly set all of the settings in the slaves and Units.
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NX-series CPU Unit Hardware User's Manual (W535)