Hitachi NES1-002LB, Краткое руководство пользователя

Страница: 163 / 295

Chapter 8 Communication Functions
8 - 9
8.6 Explanation of function codes
(A) Read Coil Status [01h]
This function reads the status (ON/OFF) of selected coils. An example follows below.

Read intelligent input terminals [1] to [5] of an inverter having a slave address “8.”

This example assumes the intelligent input terminals have terminal states listed below.
Item Data
Intelligent input
terminal
[1] [2] [3] [4] [5]
Coil number 7 8 9 10 11
Coil Status ON OFF ON OFF OFF
Query: Response:
No. Field Name
Example
(Hex)
No. Field Name
Example
(Hex)
1 Slave address *1 08 1 Slave address 08
2 Function code 01 2 Function code 01
3 Coil start address *4
(high order) 00 3 Data size (in bytes) 01
4 Coil start address *4
(low order) 06 4 Coil data *3 05
5 Number of coils
(high order *2) 00 5 CRC-16 (high order) 92
6 Number of coils
(low order *2) 05 6 CRC-16 (low order) 17
7 CRC-16 (high order) 1C
8 CRC-16 (low order) 91
Note 1:
Broadcasting is disabled.
Note 2:
When 0 or more than 31 is specified as a number of coils, error code “03h” is returned.
Note 3:
Data is transferred by the specified number of data bytes (data size).
Note 4:
The PDU Coils are addressed starting at zero. Therefore coils numbered 1-86 are
addressed as 0-85. Coil address value (transmitted on Modbus line) is 1 less than the
Coil Number.

The data set in the response shows terminal state of coils 0007h
～
000Dh.

Data “05h = 00000101b” indicates the following assuming coil 7 is the LSB.
Item Data
Coil Number 14 13 12 11 10 9 8 7
Coil Status OFF OFF OFF OFF OFF ON OFF ON

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.