Omron SYSMAC CJ1W-EIP21, Operation Manuals

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A-23
Appendices
CJ-series EtherNet/IP Units Operation Manual for NJ-series CPU Unit (W495)
A-5
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A-5 Precautions When Accessing
External Outputs from NJ-series
CPU Units
Observe the following precautions when you access variables or I/O memory addresses that are
assigned to external outputs in an NJ-series CPU Unit.
• Precaution on Writing from External Devices, Variables That Are Assigned to External Outputs
Any value that is written to a variable that is assigned to an external output in an NJ-series CPU Unit
through a tag data link or communications instruction from an external device will be overwritten by
the execution results of the user program. The value that is written from the tag data link or communi-
cations instruction will therefore not be output to the external device.
Note Variables that are assigned to external outputs include global device variables that are assigned to I/O ports
for CJ-series Basic Output Units or EtherCAT output slaves and also global variables with AT specifications
to output bits that are assigned to CJ-series Basic Output Units.
• Precaution When Directly Writing to I/O Memory Addresses Assigned to Output Bits for CJ-series
Basic Output Units
Any value that is written to an I/O memory address that corresponds to an output bit that is assigned
to a CJ-series Basic Output Unit through a tag data link will be overwritten by the execution results of
the user program. The value that is written directly to the I/O memory address from the tag data link
will therefore not be output to the external device.