Chapter1 Overview; Features - Mitsubishi QJ71MB91 User Manual

1
OVERVIEW

CHAPTER1 OVERVIEW

This manual explains the specifications, functions, programming, and troubleshooting of
the MELSEC-Q series QJ71MB91 MODBUS
as QJ71MB91).
The QJ71MB91 is used when a MELSEC-Q series programmable controller is connected
to the MODBUS
MODBUS

1.1 Features

(1) Supporting the master function of MODBUS
Device memory
Programmable controller CPU
Device memory
Auto Refresh
1
- 1 1.1 Features
protocol system.
is a registered trademark of Schneider Electric S.A.
The QJ71MB91 supports the master function of the MODBUS
which is an open network system for factory automation, and thereby is compatible
with various MODBUS
manufacturers.
The master function includes the following two functions.
(a) Automatic communication function
By setting the automatic communication parameters, MODBUS
be automatically read from or written to the slaves at the specified intervals using
the QJ71MB91 buffer memory.
Data can be transferred between the QJ71MB91 buffer memory and
programmable controller CPU device memory by making the auto refresh setting
with the utility package (GX Configurator-MB) or by accessing any intelligent
function module device with a sequence program.
QJ71MB91
RUN ERR.
NEU. NEU.
CH1 SD SD CH2
RD RD
CH1
RS-232
SDA
1
SG
2
SDB
3
(FG)
4
RDA
5
(FG)
6
RDB
7
CH2
RS-422
/485
QJ71MB91 (Master function)
Buffer memory
Read
Read
Read
Write
Automatically issues the
R
MODBUS
request message to Slave.
Figure 1.1 Communication using the automatic communication function
* 1 The MODBUS device is defined as a device area of the slave where data can be read/written in
response to a request from the master.
interface module (hereinafter referred to
slave devices (hereinafter referred to as slave) of other
*1
RS-485
device read/write
communication
communication,
device data can
R
MODBUS
(Third party remote I/O, etc)
Holding register
R
MODBUS
(Third party sensor, etc)
Holding register
R
MODBUS
(Third party programmable
controller)
Holding register
slave device
slave device
slave device