5 - 1
5.1 Function List
5
FUNCTIONS
CHAPTER5 FUNCTIONS
This chapter explains the functions of the QJ71MB91.
5.1 Function List
The function list of the QJ71MB91 is shown below.
* 1 Dedicated instructions are not available when the QJ71MB91 is installed to a MELSECNET/H
remote I/O station or a redundant system.
* 2 When the QJ71MB91 is mounted on a MELSECNET/H remote I/O station, there are restrictions on
the function codes supported by the automatic response function.( Section 4.1 (3))
* 3 When the QJ71MB91 is mounted on a MELSECNET/H remote I/O station, there are restrictions on
the assignment range of the MODBUS device assignment function.( Section 7.3.1 (2))
(Continued on next page)
Table5.1 Function list
Function Description Reference
Master function
Automatic communication
Automatically issues device read/write request messages from the
master (QJ71MB91) to a MODBUS compatible slave device.
Section 5.2.1
Communication by dedicated
instructions
*1
Allows reading/writing of MODBUS devices at any timing with a
sequence program.
CHAPTER 10
Slave function
Automatic response function
*2
Automatically performs the processing corresponding to the
function code in the request message received from the master,
and automatically sends a response message.
Section 5.3.1
MODBUS device
assignment function
*3
Automatically converts access from the slave (QJ71MB91) to a
MODBUS device into access to a QCPU device.
Users can assign any access destination.
This allows direct access from the MODBUS compatible master
device to the programmable controller CPU device memory.
Section 5.3.2
Link operation function
This function allows the master connected to QJ71MB91’s CH1
(RS-232) communicate with several slave stations connected to
QJ71MB91’s CH2 (RS-422/485).
If the link operation function is used, a RS-232 interface (1-to-1
communication) MODBUS master device can communicate with
several MODBUS slave devices.
Section 5.3.3
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