Communication By Dedicated Instructions - Mitsubishi 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
1234
H
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 = 1234
RS-232, RS-422 or RS-485
Figure 5.11 Communication by dedicated instruction
Table5.4 Dedicated instruction list
Issues a MODBUS
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
)
H
Description
device read/write request message to a slave.
5.2 Master Function
R
MODBUS slave device
Holding register
400500 1234
H
Reference
Section 10.2
Section 10.3
5
- 16
1
2
3
4
5
6
7
8