29 PRECAUTIONS ON PROGRAMMING
29.6 Precautions on Writing Data from GOT or External Devices
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29.6 Precautions on Writing Data from GOT or External
Devices
When data is written from the GOT or external devices, the tracking data may not be applied to the CPU module of the new
control system depending on the timing of system switching cause to be caused, such as power-off.
Consequently, data that is written from the GOT or external devices before system switching may be lost. Write the data again
after the system switching.
29.7 Precautions on Outputting in the Middle of the
Scan
When values are output during execution of a program with the following devices or setting, the program will be executed
again from the step 0 in the new control system after system switching. Therefore, values may be output twice, before and
after system switching. Output results may differ between the two outputs.
• Link direct device (Jn\Y)
• Direct access output (DY)
• Refresh at execution of a specified program ("Refresh Group Setting" of "Program Setting")
Before outputting values with one of the above devices or setting, check that the above operation does not cause any problem
in the system design phase. If any problem occurs, do not perform the external output until the status of the received output
signal becomes stable, or take other measures with external circuits.
In the program of the redundant system, performing the output refresh by the END processing is
recommended instead of outputting with the link direct device (Jn\Y), direct access output (DY), or refresh at
execution of a specified program ("Refresh Group Setting") in the middle of the scan.
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