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.

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