R0
Master
communication
clear to send flag
R100
UNITSEL U0 U1
RECV.US DT0U2 DT100H0301 H0
XC YC
Master
communication
sending flag
R100
RECV
execution
Settings for the communication
port
S1: Slot 0 (U0)
S2: COM1 (U1)
RECV execution start conditions
Clear to send flag: ON
Sending flag: OFF
RECV processing
S1: MODBUS code (H03) and
partner station no. (H01)
S2: Partner station address (H0)
(H0: Respond to 400001)
n: Data amount (U2)
D1: Data storage area (DT100)
D2: Execution result code (DT0)
(Note 1) Operand [S1] of RECV instruction is specified by combining two hexadecimal digits of MODBUS
function code with two hexadecimal digits of partner device station number.
(Note 2) When the partner device is FP series PLC, Operand [S2] of RECV instruction can be specified using
the device number.
■
Time chart (in the case of SCU)
Checks that the
flag is OFF
RECV execution
Master communication
sending flag
（YC,YD,YE,YF）
Master communication
sent flag
（Y0,Y1,Y2,Y3）
Data sending
Response reception
processing
clear to send flag
（XC,XD,XE,XF）
Checks that the
flag is ON
RECV Instruction executable conditions
Clear to send flag (XC,XD,XE,XF): ON
Sending flag (YC,YD,YE,YF): OFF
Sent flag (Y0,Y1,Y2,Y3):
Normal completion: OFF
Abnormal completion: ON
Sending flag (YC,YD,YE,YF):
While sending: ON, Sending done: OFF
● The case of SCU shows the case that it is used in the following combination.
• COM.0 port equipped in the CPU unit
• Communication cassettes attached to the CPU unit (COM.1 to COM.2 ports)
• Communication cassettes attached to the serial communication unit (COM.1 to COM.4
ports)
● The communication cassette (Ethernet type) does not support MODBUS.
15.7 RECV (MODBUS Master: Function Code Specification)
WUME-FP7CPUPGR-12 15-47
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