Mitsubishi Electric FX3U-232-BD User Manual page 599

FX Series PLC User's Manual - Data Communication Edition
Non-Protocol Communication (RS/RS2 Instruction)
2. Handling of 8-bit data (when M8161 is set to ON)
M8000
8-bit mode
M8161
X010
FNC 80
RS
STX
Send data
(PLC 
Header
external
equipment)
STX
Receive data
(external
Header
equipment 
PLC)
1) Send data and amount of remaining data
Send data
SD (TXD)
Amount of remaining
data
D8122
2) Receive data and amount of received data
Receive data
RD (RXD)
Amount of received
data
D8123
Caution on other instructions using M8161
M8161 is shared by RS, ASCI, HEX, CCD, and CRC (provided only in FX
If M8161 is changed during the sending/receiving operation of the RS instruction, the data may not be
received normally.
S  D 
m
D200 K 4 D500 K 10
D200 lowest- D201 lowest- D202 lowest-
order byte order byte order byte
Head address specified by S 
Number of bytes to be sent specified by "m"
D500 lowest- D501 lowest- D502 lowest-
order byte order byte order byte
Head address specified by D 
They cannot exceed the upper limit number of devices (bytes) to be
received, specified by "n". When the PLC receives the terminator (ETX) or
"n" data, receiving is completed.
4
3
2
1
0
4
3
2
1
0
16-bit data
Ignored
n
Highest-order 8-bits are ignored,
and only the lowest-order 8-bits are
regarded as valid data.
D203 lowest-
ETX
order byte
Terminator
D503 lowest- D504 lowest-
order byte order byte
6
When the receiving
5
complete flag M8123
is reset, the amount of
received data is reset
also.
3U
6 Creating Programs (RS Instruction)
6.2 How to Use RS Instruction
Lowest-order 8-bit
D505 lowest-
ETX
order byte
Terminator
and FX PLCs) instructions.
3UC
A
B
C
D
E
F
G
H
I
Apx.A
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