Mitsubishi MELSEC LJ71C24, User Manual

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10 DATA COMMUNICATION USING THE NONPROCEDURAL PROTOCOL
10.1 Data Reception from the External Device
This section explains data reception from the external device.
10.1.1 Receiving methods
The following shows the methods for receiving data in any format using the
nonprocedural protocol.
There are two methods for receiving data: the "reception via receive complete code"
for receiving variable length messages, and the "reception via received data count" for
receiving fixed length messages.
The receive complete code and received data count used for data reception can be
changed to any setting values by the user using GX Works2.
S
T
X
A B C D E F G H
E
T
X
10
STX
D
F
H
B
A
G
E
C
ETX
(00
H
) (0A
H
)
(41
H
) (02
H
)
(43
H
)
(42
H
)
(45
H
) (44
H
)
(47
H
) (46
H
)
(03
H
) (48
H
)
(02
H
) (41
H
) (42
H
) (43
H
) (44
H
) (45
H
) (46
H
) (47
H
) (48
H
) (03
H
)
Receive complete
code
External device
Head data
Send data
Receive area
(buffer memory)
C24
Receive data
count
Receive data
2) 3)
INPUT
instruction
1)
Reception data
read request
CPU module
1) When data are received from the external device using either "reception via
receive complete code" or "reception via received data count" method, the
reception data read request (X3/XA) turns ON.
2) Control data are stored in the device designated with the INPUT instruction.
3) When the INPUT instruction is executed, receive data is read from the reception
data storage area of the buffer memory.
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