Toho Electronics TTX-800 Operation Manual page 9

3.3.2 Structure of the MODBUS RTU Response Message (Data Transmission from This Product to Upper Computer)
■ See "3.3.3
Explanation of MODBUS RTU Codes" for codes a) to h).
3.3.2.1 Response Message for Read Request Message
a) Slave Address
b) Function Code
f) Number of Bytes
Data for the First Register
(Lower Word)
g)
Data for the First Register
(Upper Word)
e) CRC-16
3.3.2.2 Response Message for Write/Save Request Message
a) Slave Address
b) Function Code
c) Register Address
d) Number of Registers
e) CRC-16
3.3.2.3 Response Message for the Error
a) Slave Address
b) Function Code
h) Error Number
e) CRC-16
01H
03H
04H Number of Registers x 2
Upper 0AH ③
Lower A1H ④
Data structure is ①②③④H.
Upper 00H ①
(① represents 1 byte)
②
Lower 00H
Lower A8H
Upper 09H
01H
10H
Upper 01H
First register address
Lower 00H
Upper 00H
2 (fixed)
Lower 02H
Lower 40H
Upper 34H
01H
83H ← In case of error, the value that consists of
the function code of request message +80H
03H
will be set.
Lower 01H
Upper 31H
- 9 -