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10-2
Chapter 10. PLC Link Communication
The cyclic transfer scan cycle and cyclic data transfer operations are as follows.
In each cycle, data transfer is executed for all sheets whose data has not been
transferred.
Sheets that are in progress but cannot be completed in time are done immediately
after the transfer is complete. For the sheets for which completion of data transfer
continues to be delayed, transfer is executed consecutively with no pause.
Cyclic transfer scan cycle
Cyclic data
transfer sheet 1
Cyclic data
transfer sheet 2
Executed continuously if completion is continually delayed
Processing
Stopped
Processing
Stopped
Handling Precautions
•
If the cyclic transfer scan cycle is too short for the amount of data to be
transferred, the cyclic data transfer process may be delayed continuously,
resulting in all sheets being executed consecutively instead of periodically.
This means that data is transferred on a cycle longer than the [Cyclic transfer
scan cycle] setting.
•
If a process such as CDS writing is being executed, data may not be transferred
in the specified cycle.
•
The normal memory area and RAM area are available for the data written from
the PLC to the C7G.
Chapter 9. User-defined Addresses
z
z
Triggered data transfer
Data from the controller is transferred to the PLC when the trigger device is
detected turning from OFF to ON. Data can also be transferred from the PLC to the
controller.
Major applications:
•
Changing the controller settings (SP value, PID setting, etc.) from the PLC
•
Changing the controller operations (RUN/READY mode selection, etc.) from the
PLC