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Read Holding Register [03h]:
This function reads the contents of the specified number of consecutive holding registers
(of specified register addresses). An example follows below.
• Reading Trip monitor 1 factor and trip frequency, current, and voltage from an
inverter having a slave address “1”
• This example assumes the previous three trip factors are as follows:
X200
Command
D081
(factor)
D081
(frequency)
D081
(output current)
D081
(DC-bus Voltage)
Register
Number
0012h 0014h 0016h 0017h
Trip factor Over-Current
(E03)
9.9Hz 3.0A 284V
Query: Response:
No. Field Name
Example
(Hex)
No. Field Name
E
xamp
l
e
(Hex)
1 Slave address *1 01 1 Slave address 01
2 Function code 03 2 Function code 03
3 Register start address
*3
(high order)
00 3 Data size (in bytes) *2 0C
4 Register start address
*3
(low order)
11 4 Register data 1 (high order) 00
5 Number of holding
registers (high order)
00 5 Register data 1 (high order) 03
6 Number of holding
registers(low order)
06 6 Register data 2 (high order) 00
7 CRC-16 (high order) 95 7 Register data 2 (low order) 00
8 CRC-16 (low order) CD 8 Register data 3 (high order) 00
9 Register data 3 (low order) 63
10 Register data 4 (high order) 00
11 Register data 4 (low order) 00
12 Register data 5 (high order) 00
13 Register data 5 (low order) 1E
14 Register data 6 (high order) 01
15 Register data 6 (low order) 1C
16 CRC-16 (high order) AF
17 CRC-16 (low order) 6D
Note 1: Broadcasting is disabled.
Note 2: Data is transferred by the specified number of data bytes (data size). In this
case, 6 bytes are used to return the content of three holding registers.
Note 3: The PDU Register Number are addressed starting at zero. Therefore register
numbered “0012h” are addressed as “0011h”. Register address value
(transmitted on Modbus line) is 1 less than the Register Number.
B
−
11
Appendix B