78
Write in:
Master
Request
Response
Slave
Request
Slave Address
1 ~ 255
Function Code
06h
Start Address (High)
00h ~ FFh
Start Address (Low)
00h ~ FFh
Number of Point (High)
00h
Number of Point (Low)
00h ~ FFh
Error Check (Low)
CRC
Error Check (High)
CRC
Response
Slave Address
1 ~ 255
Function Code
06h
Start Address (High)
00h ~ FFh
Start Address (Low)
00h ~ FFh
Number of Point (High)
00h
Number of Point (Low)
00h ~ FFh
Error Check (Low)
CRC
Error Check (High)
CRC
Example:
For Modbus Master, such as PLC or data collector, it uses Modbus communication protocol to get a
reading for the value of currents from the primary current transformer (register address 0x000E) on the
power meter (Modbus Slave) (Slave address 0x1). The register value is 1000.
The packet format for Request sent out by Modbus Master (PLC or data collector) is as follows:
Master Request
0x01
0x03
0x00
0x0E
0x0
0x01
CRC
Slave Address
Function Code
Start Address
(Hi)
Start Address
(Lo)
Number of
Points (Hi)
Number of
Points (Lo)
The packet format for Response responded by Modbus Slave (power meter) is as follows:
Slave Response
0x01
0x03
0x4
03
E8
CRC
After receiving response from the power meter, Modbus Master acquires the value of currents from the
primary-side current transformer (register address 0x000E), which is 1000.
Slave Address
Function Code
Byte Count
Data
