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(5) Precautions
(a) Local device setting
Device ranges set for the auto refresh target cannot be set as local devices. If set, the refresh data will not be
updated.
(b) Using the same file name as that of the program in the file register
Do not set the file register of each program as an auto refresh target device. If set, data are automatically
refreshed to the file register corresponding to the scan execution type program executed last.
(c) Transmission delay time
Data transmission delay time due to auto refresh is from 0.09ms to (1.80 + (sending side scan time + receiving
side scan time × 2))ms.
(d) Assurance of send data
Old data and new data may coexist (data inconsistency) in each CPU module due to the timing of refreshing
data in the host CPU module and reading data in other CPU modules.
The following are the methods to prevent data inconsistency in data communications by auto refresh.
• Preventing inconsistency of 32-bit data
Data inconsistency will not occur because the data transmission by auto refresh is performed only in units
of 32 bits (parameters are set in increments of 32 bits).
• Preventing inconsistency of data exceeding 32 bits
With auto refresh, data are read in descending order of the setting number in auto refresh setting
parameter. To prevent data inconsistency, use the setting number lower than the setting data as an
interlock device.