Omron SMARTSLICE - 04-2008, Operation Manual

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xvii
Operating Environment Precautions 4
• The PLC outputs may remain ON or OFF due to deposits on 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.
• When the 24-V DC output (service power supply to the PLC) is over-
loaded 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.
• Slice I/O Terminals will continue operating even if one or more I/O Units is
removed from or falls out of the Slice I/O Terminal, i.e., the other I/O Units
will continue control operations, including outputs. As a countermeasure
for such a possibility, external safety measures must be provided to
ensure safety in the system.
!WARNING
The CPU Unit refreshes I/O even when the program is stopped (i.e., even in
PROGRAM mode). Confirm safety thoroughly in advance before changing the
status of any part of memory allocated to Output Units, Special I/O Units, or
CPU Bus Units. Any changes to the data allocated to any Unit may result in
unexpected operation of the loads connected to the Unit. Any of the following
operations may result in changes to memory status.
• Transferring I/O memory data to the CPU Unit from a Programming
Device
• Changing present values in memory from a Programming Device
• Force-setting/-resetting bits from a Programming Device
• Transferring I/O memory files from a Memory Card or EM file memory to
the CPU Unit
• Transferring I/O memory from a host computer or from another PLC on a
network
4 Operating Environment Precautions
Install the system properly according to the directions in this manual.
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 water, oil, or chemicals (General Units)
• Locations subject to acid or chemicals.
• Locations subject to shock or vibration.
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.