Read Coils [01H] - Hitachi SJ-P1 Series User Manual

Chapter 7
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".
Address Blocks
0
1
2
Modbus TCP
3
header part
4
5
6
7
8
Modbus
9
data part
10
11
Hi: high order
Lo: low order
Items
Transaction ID (Hi)
Transaction ID (Lo)
Protocol ID (Hi)
Protocol ID (Lo)
Data size (Hi)
Data size (Lo)
Unit ID
Function code
Starting adderess (Hi)
Starting adderess (Lo)
Quantity of coils (Hi)
Quantity of coils (Lo)
7-5
About the Modbus TCP
Code
15h
01h
00h
00h
00h
In the case, 6 byte lengths
06h (address 6 through 11).
FFh
01h
00h
In the case, "0000h"
00h ("0001h" minus 1).
00h In the case, the quantity of
0Fh coils is 15.