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Operating Environment Precautions 4
• The PLC outputs may remain ON or OFF due to deposition or burning of
the output relays or destruction of the output transistors. As a counter-
measure for such problems, external safety measures must be provided
to ensure safety in the system.
!WARNING When the 24-VDC output (service power supply to the PLC) is overloaded or
short-circuited, the voltage may drop and result in the outputs being turned
OFF. As a countermeasure for such problems, external safety measures must
be provided to ensure safety in the system.
!Caution When wiring crossovers between terminals, the total current for both terminals
will flow in the line. Check the current capacities of all wires before wiring
crossovers.
!Caution Tighten the screws on the terminal block of the AC Power Supply Unit to the
torque specified in the operation manual. The loose screws may result in
burning or malfunction.
!Caution Execute online edit only after confirming that no adverse effects will be
caused by extending the cycle time. Otherwise, the input signals may not be
readable.
4 Operating Environment Precautions
!Caution Do not operate the control system in the following places:
• Locations subject to direct sunlight.
• Locations subject to temperatures or humidity outside the range specified
in the specifications.
• Locations subject to condensation as the result of severe changes in tem-
perature.
• Locations subject to corrosive or flammable gases.
• Locations subject to dust (especially iron dust) or salts.
• Locations subject to exposure to water, oil, or chemicals.
• Locations subject to shock or vibration.
!Caution Take appropriate and sufficient countermeasures when installing systems in
the following locations:
• Locations subject to static electricity or other forms of noise.
• Locations subject to strong electromagnetic fields.
• Locations subject to possible exposure to radioactivity.
• Locations close to power supplies.
!Caution The operating environment of the PLC System can have a large effect on the
longevity and reliability of the system. Improper operating environments can
lead to malfunction, failure, and other unforeseeable problems with the PLC
System. Be sure that the operating environment is within the specified condi-
tions at installation and remains within the specified conditions during the life
of the system.
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