Version 4.0
- 11 -
6. DETAILS OF MESSAGE
6.1 Read-out of Word Data [Function Code: 03]
Read the contents of holding registers (0000~ 007D) in the slave. Broadcast is not
possible.
1. Message composition
Command message composition
Address
Function
Starting Address Word Number*
CRC-16
01~FF
03
0xxx
0001~007E
Low-order
byte
High-order
byte
1 byte
1 byte
2 byte
2 bytes
2 bytes
*Maximum word number = 7E
Response message composition
Address
Function
Byte Number *
Word Data
CRC-16
01 ~ FF
03
02~FC
Low-order
byte
High-order
byte
1 byte
1 byte
1 bytes
N bytes
2 bytes
*Byte number = Word number
×
2
2. Message transmission (example)
The following show an example of reading the Set point Value (1000) from address
No.1 controller.
Command message composition
Address
Function
Starting Address
Word Number
CRC-16
01
03
0000
0001
840A
Response message composition
Address
Function
Byte Number
Word Data
CRC-16
01
03
02
03E8
B8FA