Panasonic FP7 Series User Manual page 114

8.3 MODBUS RTU Master Communication (RECV)
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I/O allocation (in the case of CPU with built-in SCU)
COM Port No.
1 2 0
XC XD XE
YC YD YE
Y0 Y1 Y2
(Note 1) Each contact is used for reading the operation state. Do not write over it with a user program.
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I/O allocation (in the case of Serial Communication Unit)
COM Port No.
1 2 3
XC XD XE
YC YD YE
Y0 Y1 Y2
(Note 1) Each contact is used for reading the operation state. Do not write over it with a user program.
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Precautions during programming (in the case of SCU)
● Use the UNITSEL instruction immediately before the SEND/RECV instruction to specify a
target port for communication.
● Master communication is only enabled when MEWTOCOL or MODBUS is selected. Confirm
that the "master communication clear to send flags" (XC to XF) are ON for the corresponding
channel, and execute the SEND/RECV instruction.
● Another SEND/RECV instruction cannot be executed for a communication port where master
communication is in progress. Confirm that the "master communication sending flags" (YC to
YF) are OFF, and execute the instruction.
● A SEND/RECV instruction cannot be executed for a port where slave communication is in
progress. If there is no response, the "master communication sending flags" (YC to YF)
remain ON during the time-out period set in the CPU configuration.
● Up to 16 SEND/RECV instructions can be executed simultaneously for differing COM ports.
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Sample program (in the case of CPU with built-in ET-LAN)
● This program sends MODBUS commands (03) from the LAN port of the CPU unit, reads the
data from the data area of an external device 400001 to 400002 (MODBUS address 0000H
to 0001H), and writes the content into PLC's data register DT100 to DT101.
8-18
Name
Master
communication
clear to send flag
Master
communication
sending flag
Sent flag
Name
4
Master
XF communication
clear to send flag
Master
YF communication
sending flag
Y3 Sent flag
Turns ON when MEWTOCOL-COM, MEWTOCOL7, or MODBUS-
RTU is set for the communication mode, and the unit is in the
RUN mode.
Turns ON during sending data based on SEND/RECV instruction.
Turns OFF when the sending process is completed.
Reports completion result of sending data in genera-purpose
communication or master communication.
(Normal completion: 0, Abnormal completion: 1)
Turns ON when MEWTOCOL-COM, MEWTOCOL7, or
MODBUS-RTU is set for the communication mode, and the unit
is in the RUN mode.
Turns ON during sending data based on SEND/RECV
instruction.
Turns OFF when the sending process is completed.
Reports completion result of sending data in genera-purpose
communication or master communication.
(Normal completion: 0, Abnormal completion: 1)
Description
Description
WUME-FP7COM-07