Safety Precautions
14
NX-series NX1P2 CPU Unit Hardware User’s Manual (W578)
If there is interference in remote I/O communications or if a major fault level
error occurs, output status will depend on the products that are used.
Confirm the operation that will occur when there is interference in communi-
cations or a major fault level error, and implement safety measures.
Correctly set all of the settings in the slaves and Units.
If external power supplies for Units, 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.
Unintended outputs may occur when an error occurs in variable memory. As
a countermeasure for such problems, external safety measures must be pro-
vided 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.
The NX-series Controller continues normal operation for a certain period of
time when a momentary power interruption occurs. This means that the
NX-series Controller may receive incorrect signals from external devices that
are also affected by the power interruption. Accordingly, take suitable
actions, such as external fail-safe measures and interlock conditions, to
monitor the power supply voltage of the external device as required.
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 other causes. Not doing so may result in serious acci-
dents due to incorrect operation.
Voltage and Current Inputs
Make sure that the voltages and currents that are input to the slaves and
Units are within the specified ranges.
Inputting voltages or currents that are outside of the specified ranges may
cause accidents or fire.
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