RuiDeng DPH5005 - MODBUS Communication Examples; Reading Voltage and Current (Function 0 x03); Setting Voltage (Function 0 x06); Setting Voltage and Current (Function 0 x10)

Three examples of communication using the three available MODBUS
Functions Codes supported on this device. (0x03) (0x06) and (0x10)
1 : Read the displayed output voltage and current value. (Using Function 0x03)
Message format sent from Host:
Host sends
Number of
bytes
Information sent
Notes
Slave address
1
01
From host to slave address 01H
Function code
1
03
Read holding register(s)
Register starting
address
2
0002H
Register starting address
Number of registers to
read
2
0002H
A total of 2 registers (4 byte = 2
words)
CRC Checksum:
2
65CBH
CRC Checksum from Host:
For example if the displayed values are 05.00V , 5.000A , The Slave return response would be:
Slave responds
Number of
bytes
The
information
returned
Notes
Slave address
1
01
From slave address 01H
Function code
1
03
Read holding register
Number of bytes read
1
04
A total of 4 Bytes
The contents of 1
st
register read
2
01F4H
Output voltage display
values
The contents of 2
nd
register read
2
1388H
Output current display value
CRC Checksum:
2
B76BH
CRC Checksum from Slave
2 : Host to set the voltage to 24.00V. (Using Function 0x06)
Message format sent from host:
Host sends
Number of
bytes
Information
sent
Notes
Slave address
1
01H
From host to slave address
01H
Function code
1
06H
Write single register
Register address
2
0000H
Register address
The value to write to the register
2
0960H
Set the output voltage
CRC Checksum
2
8FB2H
CRC Checksum from host
Message format returned from Slave:
Slave responds
Number of
bytes
The
information
returned
Notes
Slave address
1
01H
From slave address 01H
Function code
1
06H
Write single register
Register address
2
0000H
The Register address
The contents of the register read
2
0960H
Value read
CRC Checksum
2
8FB2H
CRC Checksum from slave
3 : Host to set the voltage to 24.00V , The current 1.500A. (Using Function 0x10 (decimal 16))
Message format sent from HOST:
Host sends
Number of
bytes
Information
sent
Notes
Slave address
1
01H
From host to slave address
01H
Function code
1
10H
Write multiple registers
Register starting address
2
0000H
Register the starting address
Quantity of registers to write to
2
0002H
2 registers
Number of bytes to write
1
04H
4 Bytes = 2 words = 2 registers
Contents of 1
st
register
2
0960H
Set the output voltage
Contents of 2nd register
2
05DCH
Set the output current
CRC Code:
2
F2E4H
CRC Checksum from Host: