Explanation Of Function Codes - Hitachi SJ200 Series Instruction Manual

B–10
Network Protocol Reference

Explanation of function codes

Read Coil Status [01h]:
This function reads the status (ON/OFF) of selected coils. An example follows below.
• Read intelligent input terminals [1] to [6] of an inverter having a slave address "8."
• This example assumes the intelligent input terminals have terminal states listed below.
Intelligent input
terminal
Coil Status
Query:
No.
1
2
3
4
5
6
7
8
Note 1:
Note 2:
• The data set in the response shows terminal states of coils 7 to 14.
• Data "17h = 00010111b" indicates the following assuming coil 7 is the LSB.
Coil Number
Coil Status
Item
[1] [2]
ON ON
Field Name
Slave address *1
Function code
Coil start number
(high order)
Coil start number
(low order)
Number of coils
(high order) *2
Number of coils (low
order) *2
CRC-16 (high order)
CRC-16 (low order)
Broadcasting is disabled.
When 0 or more than 32 is
specified as a number of coils,
error code "03h" is returned.
Item
14
OFF OFF
Data
[3] [4]
ON OFF
Response:
Example
No.
(Hex)
08 1
01 2
00 3
4
07
5
6
00
Note 3:
06
0D
50
Data
13 12 11
OFF ON
[5] [6]
ON OFF
Example
Field Name
(Hex)
Slave address
Function code
Data size (in bytes)
Coil data *3
CRC-16 (high order)
CRC-16 (low order)
Data is transferred by the
specified number of data bytes
(data size).
10 9 8
OFF ON ON
08
01
01
17
12
1A
7
ON