Communication By Dedicated Instructions - Mitsubishi Electric QJ71MB91 User Manual

5
FUNCTIONS

5.2.2 Communication by dedicated instructions

The dedicated instructions allow reading/writing of MODBUS devices at any timing with a
sequence program.
Programmable
controller CPU
Command
[Z.MBRW
Device memory
1234H
The following is a list of available dedicated instructions.
Dedicated
instruction
MBRW
MBREQ
QJ71MB91
(Master
function)
Request message
]
(Read request for holding register 400500)
Response message
(Holding register 400500 = 1234H)
Figure 5.11 Communication by dedicated instruction
Table5.4 Dedicated instruction list
Issues a MODBUS device read/write request message to a slave.
With this instruction, a request message can be sent to a slave in any
given Protocol Data Unit format.
5.2.2 Communication by dedicated instructions
RS-232, RS-422 or RS-485
Description
5.2 Master Function
MODBUS Slave device
Holding register
400500 1234H
Reference
Section 10.2
Section 10.3
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