Mitsubishi Electric MELSEC Q Series User Manual page 180

(4) Precautions
(a) Local device setting
Device ranges set for the use of the auto refresh cannot be set to local devices.
If set, the refresh data will not be updated.
(b) Setting for using the same file name as the program in the file register
Do not set devices for the use of the auto refresh in the file register for each program.
If set, auto refresh will be performed on the file register that corresponds to the last scan execution type
program executed.
(c) Transmission delay time
Data transmission delay time due to auto refresh is from 0.09 ms to (1.80 + (Sending side scan time +
Receiving side scan time
(d) Assurance of data sent between CPUs
Due to the timing of data send from the host CPU and auto refresh in any of other CPUs, old data and new data
may be mixed (data separation) in each CPU.
The following shows the methods for avoiding data separation at communications by auto refresh.
1) 32-bit data separation
Transfer data with auto refresh method in units of 32 bits. Since auto refresh is set in units of 32 bits, 32-bit
data does not separate.
2) Data consistency for data exceeding 32 bits
In auto refresh method, data are read in descending order of the setting number in auto refresh setting
parameter.
Transfer data separation can be avoided by using the transfer number lower than the transfer data as an
interlock device.
Figure 4.38 shows a program example for interlocking between CPU No.1 and CPU No.2.
<Parameter setting>
CPU No.1 auto refresh setting
Data communication
range for each CPU
CPU Transfer
No. No.
Number
of Start
points
Transfer 1 2 0
CPU
No.1
Transfer 2 10 2
CPU
Transfer 1 2 0
No.2
In the above parameter settings, use M0 as an interlock device for CPU No.1 (data setting completion bit)
and M32 as an interlock device for CPU No.2 (receive data processing completion bit).
2)) ms.
Table4.10 Example for parameter setting for interlock program
Device setting
for data
communication
Directio
End Start End
1 M0 M31
11 D0 D9
1 M32 M63
CHAPTER4 COMMUNICATIONS BETWEEN CPU MODULES
CPU No.2 auto refresh setting
CPU specific send range
CPU Transfer
n No. No.
Number
of
points
Transfer 1 2
CPU
No.1
Transfer 2 10
CPU
Transfer 1 2
No.2
Device setting
for data
communication
Start End Start End
0 1 M0 M31
2 11 D100 D109
0 1 M32 M63
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