MITSUBISHI ELECTRIC MOTION CONTROLLERS Q172DCPU - Manual (Page 61)

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2 MULTIPLE CPU SYSTEM
(5) Precautions
(a) Assurance of data sent between CPUs
Due to the timing of data sent from the self CPU and automatic refresh in
any of the other CPUs, old data and new data may become mixed (data
separation).
The following shows the methods for avoiding data separation at
communications by automatic refresh.
1) Data consistency for 32 bit data
Transfer data with automatic refresh method is in units of 32 bits. Since
automatic refresh is set in units of 32 bits, 32-bit data does not separate.
• For word data
2 words data can be prevented from separating by using an even
number to set the first number of each device in automatic refresh
setting.
2) Data consistency for data exceeding 32 bits
In automatic refresh method, data is read in descending order of the
setting number in automatic refresh setting parameter.
Transfer data separation can be avoided by using a transfer number
lower than the transfer data as an interlock device.