Hitachi SJ-P1 Series, Руководство пользователя

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7-5
Chapter 7 About the Modbus TCP
7.2.5 Read coils [01h]
This function code is used to read status of coils.
[Request]
The Request specifies the starting address, i.e. the
address of the first coil specified, and the number
of coils.
(Example)
Reading 15 coils with the coil number of "0001h"
through "000Fh".
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 01h
8 Starting adderess (Hi) 00h In the case, "0000h"
("0001h" minus 1).
9 Starting adderess (Lo) 00h
10 Quantity of coils (Hi) 00h
In the case, the quantity of
coils is 15.
11 Quantity of coils (Lo) 0Fh