Mitsubishi QJ71MB91, Руководство пользователя

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1
OVERVIEW
1.1 Features
1
- 2
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SYS
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S
P
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CIFICA
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ONS
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MODB
US
(R)
S
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NDA
RD
FUN
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TIO
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FUNC
TI
ON
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PR
E
-O
PER
A
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AL
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OCED
URE
S A
ND
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TTINGS
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P
A
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MET
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R S
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TTI
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8
UTIL
ITY P
A
CK
AGE
(G
X Co
nf
ig
u
rat
o
r-M
B)
(b) Communication using dedicated instruction
Dedicated instructions can be used to make communication from sequence
programs at any timing.
The following dedicated instructions are available for the QJ71MB91. (
CHAPTER 10)
1) MBRW instruction
Reads or writes MODBUS device data from or to a slave.
This enables reading slave data to the programmable controller CPU device
memory or writing programmable controller CPU data to slaves.
2) MBREQ instruction
The user-determined request message format (function code + data unit) can
be issued to the slaves.
Figure 1.2 Communication using dedicated instruction
[Z.MBRW ]
Command
QJ71MB91
(Master
function)
400500
Response Message ( Holding register 400500= 1234H)
Programmable
controller CPU
Device memory
1234
H
Request message
(Read request for holding register 400500)
Response message
(Holding register 400500 = 1234
H
)
1234
H
Holding register
R
MODBUS Slave device
RS-232, RS-422 or RS-485