Hitachi EH-150 Series - Page 107

Chapter 6 Communication Mode
6 - 65
Modbus Slave
 Function code 0x02 (Read Input Status)
For EH-SIO, this function code means “Read status of input (X)”. Broadcasting is not supported.
(1) Query
The start address of the input bit and the number of inputs to be read are specified in the query.
« Note »
It is necessary to change the bit number to hexadecimal number. (When using I/O mapping, the bit No. in a module
are hexadecimal number.)
For example, when reading from X1232 (u-1, s-2, and bit No.-32), the start address is set to H1220.
(2) Response
Response is sent back automatically according to query. The meaning of the data field bit, with 1 for ON and 0 for
OFF, the first LSB data will be in the state of the specified I/O number. Data is handled as 1 byte. If data less than 1
byte is requested, the rest part will be 0.
« Note »
If requested address or a part of data is not assigned as input, exception response will be returned.
(3) Example
Read the status of X2408-X2415 (8 points) in the slave 05.
Query
Response
Field name
Example
(HEX)
Field name
Example
(HEX)
Slave address
0 5
Slave address
0 5
Function code
0 2
Function code
0 2
Input status head address (upper)
2 4
Number of data bytes
0 1
Input status head address (lower)
0 8
Input status data
C 5
Input status number (upper)
0 0
Error check
[CRC]
Input status number (lower)
0 8
Error check
[CRC]
Data in X2408 – X2415 is stored in byte (LSB = X2408).
X
u
s
Change to a hexadecimal number
Remains as is
Remains as is
X2400
OFF
ON
ON
ON
ON
ON
OFF
ON
ON
ON
OFF
OFF
X2415
X2408
ON
OFF
ON
ON
C
5