Hitachi SJ7002 Series Instruction Manual page 308

Explanation of
Function Codes
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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
(coils 13 and 14 are OFF).
Item
Intelligent input terminal
Coil number
Terminal status
Query:
No. Field Name
1 Slave address *1
2 Function code
3 Coil start number
(high order)
4 Coil start number (low
order)
5 Number of coils (high
order) *2
6 Number of coils (low
order) *2
7 CRC-16 (high order)
8 CRC-16 (low order)
Note 1: Broadcasting is disabled.
Note 2: The starting coil number is one
less than the number of the coil to
be read first.
Note 3: When 0 or more than 32 is
specified as a number of coils,
error code "03h" is returned.
• 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.
Item
Coil number 14
Coil status OFF
• When a read coil is outside the defined coils, the final coil data to be transmitted contains
"0"as the status of the coil outside the range.
• When the Read Coil Status command cannot be executed normally, see the exception
response.
[1] [2] [3]
7 8 9
ON ON ON
Response:
Example
No.
(hex)
08 1
01 2
00 3
4
06
5
6
00
Note 4: Data is transferred by the specified
06
5C
90
Data
13 12 11
OFF OFF ON
SJ700 Inverter
2
Data
[4] [5]
10 11
OFF ON
Example
Field Name
(hex)
Slave address
Function code
Data size (in bytes)
Coil data *4
CRC-16 (high order)
CRC-16 (low order)
number of data bytes (data size).
10 9 8
OFF ON ON
B–25
[6]
12
OFF
08
01
01
17
12
1A
7
ON