Recv (Mewtocol Master / Modbus Master) - Panasonic FP7 Series User Manual

8.3 MODBUS RTU Master Communication (RECV)
● Use the UNITSEL instruction immediately before the SEND/RECV instruction to specify a
target port for communication.
● Master communication is only valid when MODBUS is selected. Confirm that the "Master
communication Clear to send flag" (XC - XF) for the targeted channel is ON, and execute
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 active flag"
(YC - YF) is OFF, and execute instruction.
● A SEND/RECV instruction cannot be executed for a port where slave communication is in
progress.
● If no response is received, the "Master communication Sending active flag" (YC - YF) remains
ON throughout the timeout setting time specified in CPU configuration.
● Up to 16 SEND/RECV instructions can be executed simultaneously for differing COM. ports.

8.3.2 RECV (MEWTOCOL Master / MODBUS Master)

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Ladder diagram
(Note 1) The above figure shows the case that S1=U0 (CPU unit with built-in SCU) and S2=U1 (port number 1)
are specified by the UNITSEL instruction.
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Available operation units (●: Available)
Operatio
bit
n unit
i
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List of operands
Operand Description
S1 Partner station number
S2 Starting address of the device in the sender data area of the partner unit
n Number of received data
D1 Starting address of the device in the receiver data area of the master unit
D2 Starting address of the device area of the master unit that stores the execution result code (1 word)
8-6
US SS
● ●
UL SL SF DF
WUME-FP7COM-07