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MELSEC-Q
1 OVERVIEW
(3) Concurrent operation of master and slave functions
The master and slave functions can be operated concurrently.
This enables flexible construction of a MODBUS
R
/TCP communication-based
system.
(a) Example of communication between QJ71MT91 and third
party devices
Third party
programmable controller
(Master)
Third party remote I/O
(Slave)
QJ71MT91
(Master/slave function)
Master
Slave
Master
Slave
Ethernet
1)
2)
Request
message
Response
message
Response
message
Request
message
1) In response to a request message from the master, the QJ71MT91
operates as a slave and returns a response message.
2) The QJ71MT91 operates as a master, and issues a request message
to the slave.
(b) Example of communication between QJ71MT91 and
QJ71MT91
The both functions can be operated bi-directionally between QJ71MT91
and QJ71MT91.
QJ71MT91
(Master/slave function)
Ethernet
QJ71MT91
(Master/slave function)
Request
message
Response
message
(4) Support of GX Developer connection via Ethernet
GX Developer can be connected to Ethernet via the QJ71MT91.
This enables the maintenance of the programmable controller CPU via Ethernet.
Ethernet
GX Developer
QJ71MT91