7 - 2 7 - 2
MELSEC-Q
7 PROGRAMMING FOR EXECUTING THE MASTER FUNCTION
(4) When data of multiple words is sent from/received in the buffer memory of the
QJ71DN91, data inconsistency may occur.
When sending/receiving data of multiple words, use Data consistency dedicated
instruction (DNTMRD, DNTMWR, DNTSRD, DNTSWR).
REMARK
With MOV or FROM/TO instruction, data inconsistency can be avoided by checking
data transfer.
The following shows an example in which data transfer is checked by providing a
handshake area at the end of send/receive data.
QJ71DN91 master
Master function
receive data
700
H
Master function
transmit data
900
H
901
H
902
H
903
H
D0
D1
D2
QJ71DN91 slave
Slave function
transmit data
C00
H
Slave function
receive data
B00
H
B01
H
B02
H
B03
H
D100
D101
D102
703
H
C03
H
Receive data
Transmit
data
Programmable controller CPU
(Receive complete flag)
(Receive completion
notification flag)
(Transmit complete flag)
701
H
702
H
C01
H
C02
H
(Transmit request flag)
Programmable controller CPU
1)Transmit request
M0
2)
3)
4)
5)
Transmit data
Receive data
7)
6)
7
Содержание QJ71DN91
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