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4. Operation Method
RS485 Communication Function
5. Communication Examples
5.1 Read communication example
Example) Request message:
A request for reading PV is transmitted to the unit set at address 02.
Reply message from the unit to this request message: The data of PV (00123) is returned.
S
T
X
0
2
R
P
V
1
E
T
X
B
C
C
① ② ③ ④ ⑥ ⑦
① ② ⑧ ④ ⑤ ⑥ ⑦
Code
Symbol/Data
ASCII code
*2
①
Start Code
STX
02H
②
Address
02
30H 32H
③
Request (Read)
R
52H
④
Identifier
*1
PV1
50H 56H 31H
⑤
Numeric Data
00123
30H 30H 31H 32H 33H
⑥
End Code
ETX
03H
⑦
BCC data
Request
61H
Reply
02H
⑧
Acknowledgement code
ACK
06H
*1): See "7. List of Identifiers/Commands."
*2): For ASCII codes, see "8. List of ASCII Codes."
S
T
X
0
2
A
C
K
P
V
1
0
0
1
2
3
E
T
X
B
C
C
Read request message
(transmitted from the host computer)
Reply message (returned from the unit)