Mitsubishi Electric MELSEC Q Series User Manual page 267

(5) Precautions
(a) Auto refresh execution
Auto refresh is executed when the CPU module is in the RUN, STOP, or PAUSE status.
(b) Transmission delay time
A transmission delay caused by auto refresh will be within the following range.
0.09 ms to (1.80 + (Sending-side write time
*1 : For the write time of the bus interface function (QBF_ToBuf), refer to the following.
Page 475, Appendix 5
*2 : When the receiving side is a C Controller module, there is no reading cycle (i.e. 0ms).
When the receiving side is other than a C Controller module, it is the scan time on the receiving side.
(c) Assurance of data sent among CPUs
Depending on the timing of sending data from the host CPU and auto-refreshing data in another CPU, new and
old data may be mixed in the area for each CPU.
Therefore, configure an interlock program for auto refresh so that data of another CPU will not be used when
old and new data are mixed.
For the auto refresh method, transfer is performed in descending order of "Setting No." in the auto refresh setting
parameters.
Therefore, use the "Setting No." smaller than the transfer data for an interlock device so that data of another CPU will not be
used when old and new data are mixed.
For an example of program for interlocking, refer to the following.
Page 259, Section 14.1.2 (4)
CHAPTER 14 FUNCTIONS USED BY MULTIPLE CPU SYSTEM
*1
+ Receiving-side reading cycle
*2
 2)) ms
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