Instruction Manual

33
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 V1
E
T
X
B
C
C
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
Request 61H
⑦ BCC data
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 V1 0 0 1 23
E
T
X
B
C
C
① ② ⑧ ④ ⑥ ⑦ ⑤
① ② ③ ④ ⑥ ⑦
Read request message
(
transmitted from the host com
p
uter
)
Reply message (returned from the unit)