Mitsubishi QJ71MB91 - Communication by Dedicated Instructions

5
FUNCTIONS
5.2 Master Function
5.2.2 Communication by dedicated instructions
5 - 16
1
OVERVIEW
2
SYSTEM CONFIGURATION
3
SPECIFICATIONS
4
MODBUS(R) STANDARD FUNCTIONS
5
FUNCTION
6
PRE-OPERATIONAL PROCEDURES AND SETTINGS
7
PARAMETER SETTING
8
UTILITY PACKAGE (GX Configurator-MB)
5.2.2 Communication by dedicated instructions
The dedicated instructions allow reading/writing of MODBUS devices at any timing with a
sequence program.
The following is a list of available dedicated instructions.
Figure 5.11 Communication by dedicated instruction
Table5.4 Dedicated instruction list
Dedicated
instruction
Description Reference
MBRW
Issues a MODBUS device read/write request message to a slave.
Section 10.2
MBREQ
With this instruction, a request message can be sent to a slave in any
given Protocol Data Unit format.
Section 10.3
[Z.MBRW ]
Command
400500
MODBUS slave device
Holding register
1234
H
R
Programmable
controller CPU
Device memory
1234
H
QJ71MB91
(Master function)
Request message (Read request for holding register 400500)
Response message (Holding register 400500 = 1234H)
RS-232, RS-422 or RS-485