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4. Operating procedures
Useful functions (RS485 communication function)
5. Communication example
5.1
Communication example to be read out
Example)
Request message: This message requests read-out of PV to the Unit addressed
to address02.
Reply message from the Unit to this: PV data (00123) is returned.
Read request message (Transmitted from a host computer)
S
T
X
0
2
R
P
V
1
E
T
X
B
C
C
① ② ③ ④ ⑥ ⑦
Reply message (Transmitted from the Unit)
① ② ⑧ ④ ⑤ ⑥ ⑦
Code
Symbol/data
ASCII code note 2)
①
Start code
STX
02H
②
Address
02
30H 32H
③
Request
（
Read
）
R
52H
④
Identifier note 1)
PV1
50H 56H 31H
⑤
Numeric data
00123
30H 30H 31H 32H 33H
⑥
End code
ETX
03H
⑦
BCC data Request
Reply
61H
02H
⑧
Acknowledgement code
ACK
06H
Note 1) See
“7.Identifier/command list”.
Note 2) For ASCII codes, see
“8.ASCII code list”.
S
T
X
0
2
A
C
K
P
V
1
0
0
1
2
3
E
T
X
B
C
C