100
SANTERNO
USER MANUAL
Byte
Name
Byte
Description
Note
1
Address code
1
1-247 (1-F7)
Slave address
2
Function code
1
0x03, 0x06, 0x10
03H, 06H, 10H
3
Data zone
2*N
0x00~0xFF
Core content of data exchange
4
Check code
2
0x00~0xFF
CRC check
Total
≤256
Nr of registers
Function code
Name
Description
03H
Read multiple registers
Read data from slave station multiple registers
06H
Write multiple registers
Pre-set multiple parameters to registers
10H
Write single register
Pre-set Single parameters to register
ADU(Application data segment)
Specification data segment
Address code
Function code
Data
Check code
B2. ICMP
B3. Function code definition
B4. Common function codes and responses
4.1 Function code 0x03, read multiple registers
Frame header START
T1-T2-T3-T4(3.5 bytes of transmission time)
Slave ADDR field
Communication ADDR : 0~247(decimal)(0 is broadcast ADDR )
Function code
03H:read slave parameters ; 06H:deliver slave command; 10H:write slave parameters
Data field
DATA
（
N-1
）
…
DATA
（
0
）
2*N bytes of data, this part is the main content of communication, but also in communication, the
core of data exchange
CRC check lo
Test value : cyclicredundancychecks(CRC check)(16BIT)
CRC check hi
Frame END
T1-T2-T3-T4(3.5 bytes of transmission time)
Standard structure of the RTU frame :
