Hitachi SJ-P1 Series - Read;Write Multiple Registers [17 H]

7-15
Chapter 7
About the Modbus TCP
7.2.12 Read/Write multiple registers [17h]
This function code performs a combination of one
read operation and one write operation. The write
operation is performed before the read.
[Request]
The request specifies the starting address and
number of holding registers to be read as well as
the starting address, number of holding registers,
and the data to be written.
(Example)
Configure the register number "2B02h (FA-10:
acceleration time monitor)" to 10.00[s].
Then, read the register number "2B04h (FA-12:
deceleration time monitor)".
Hi: high order
Lo: low order
*1) Configure the number of bytes to actually
change, not the number of hold registers.
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, 15 byte lengths
(address 6 through 20).
5
Data size (Lo)
0Fh
6
Unit ID
FFh
7
Modbus
data part
Function code
17h
8
Read starting address (Hi)
2Bh
In the case, "2B03h"
("2B04h" minus 1).
9
Read starting address (Lo)
03h
10
Quantity to read (Hi)
00h
11
Quantity to read (Lo)
02h
12
Write starting address (Hi)
2Bh
In the case, "2B01h"
("2B02h" minus 1).
13
Write starting address (Lo)
01h
14
Quantity to write (Hi)
00h
15
Quantity to write (Lo)
02h
16
Byte count *1)
04h
17
Write register value 1 (Hi)
00h
0000 03E8h
→1000d→10.00[s]
18
Write register value 1 (Lo)
00h
19
Write register value 2 (Hi)
03h
20
Write register value 2 (Lo)
E8h