Hitachi SJ-P1 Series - Reading Registers

7-7
Chapter 7
About the Modbus TCP
7.2.6 Read holding registers [03h]
This function code is used to read the contents of
a contiguous block of holding registers.
[Request]
The request specifies the starting register address
and the number of registers. In the registers are
addressed starting at zero.
(Example)
Reading information about trips ("03E9h" through
"03EDh") from the inverter.
Hi: high order
Lo: low order
Address
Blocks
Items
Code
0
Modbus TCP
header part
Transaction ID (Hi)
15h
1
Transaction ID (Lo)
01h
2
Protocol ID (Hi)
00h
3
Protocol ID (Lo)
00h
4
Data size (Hi)
00h
In the case, 6 byte lengths
(address 6 through 11).
5
Data size (Lo)
06h
6
Unit ID
FFh
7
Modbus
data part
Function code
03h
8
Starting adderess (Hi)
03h
In the case, "03E8h"
("03E9h" minus 1).
9
Starting adderess (Lo)
E8h
10
Number of registers (Hi)
00h
In the case, the number of
registers is 5.
11
Number of registers (Lo)
05h