Omron CX-PROCESS TOOL V5.2 - 12-2009 Operation Manual page 27

Application Precautions
! Caution
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Caution
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! Caution
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Caution
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! Caution
! Caution
When uploading the Loop Controller's function block data, observe the following
precautions.
When performing Upload New for Loop Control Units of version 1.5 or earlier,
data on the Edit Block Diagram Screen (function block information) will be lost,
and the block diagram showing the connections between function blocks will not
be displayed.
When performing Upload Previous, if the data in the source file currently
opened using the CX-Process Tool and the Loop Controller's function block data
does not match the registered function blocks or the data on the Edit Block Dia-
gram Screen, the data currently opened may change to illegal data.
The Loop Controller can read and write I/O memory in the CPU Unit using the
Field Terminal Function Blocks or CPU Terminal Blocks independent of the user
program (Step Ladder Program) in the CPU Unit. Do not write to the same I/O
memory words from both the Loop Controller and the CPU Unit.
To hold an analog output or contact output at a specific value (for example, the
maximum value or minimum value) when the Loop Controller stops running,
create a Step Ladder Program in the CPU Unit so that the corresponding output
bit allocated to Analog Output Unit or Contact Output Unit is set to the desired
value using an NC condition of the Loop Controller Running Flag (bit 00 in allo-
cated CIO word "n") as an input condition.
If a fatal error occurs in the CPU Unit (including fatal errors created by execution
of a FALS instruction), the Loop Controller will also stop running. To hold analog
outputs to the previous values before the stop occurred, and to set analog out-
puts to either the minimum value or maximum value, use the output hold function
of the Analog Output Unit or Analog I/O Unit.
Before turning ON the power to the PLC, make sure that the facilities are safe.
The analog output values and contact outputs from the Loop Controller are up-
dated when the power to the PLC is turned ON regardless of the operating mode
of the CPU Unit (including in the PROGRAM mode). (Internally, the analog out-
put values and contact outputs are sent from the CPU Unit to Basic I/O Units and
Analog Output Units.)
Fail-safe measures must be taken by the customer to ensure safety in the event
of incorrect, missing, or abnormal signals caused by broken signal lines, mo-
mentary power interruptions, or other causes.
Confirm that no adverse effect will occur in the system before attempting any of
the following:
• Changing the operating mode of the PLC (including the setting of the startup
operating mode).
• Force-setting/force-resetting any bit in memory
• Changing the present value or any set value in memory
Be sure that all mounting screws, terminal screws, and cable connector screws
are tightened to the torque specified in the user manuals. Incorrect tightening
torque may result in malfunction.
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