Hitachi EH-150 Series - Page 109

Chapter 6 Communication Mode
6 - 67
Modbus Slave
 Function code 0x04 (Read Input Registers)
For EH-SIO, this function code means “Read status of internal output (WM)”. Broadcasting is not supported.
(1) Query
The start address of the internal output (WM) and the number of internal outputs to be read are specified by the
query.
« Note »
A start address should specify I/O number of WM. (For WM3F1, the address is specified as H03F1.)
(2) Response
Response is sent back automatically according to query. Response is returned in an order from the high byte of the
specified address.
« Note »
If requested address or a part of data is not assigned as WM range, exception response will be returned.
(3) Example
Read the status of WM1F2-WM1F4 (3 words) in the slave 18.
Query
Response
Field name
Example
(HEX)
Field name
Example
(HEX)
Slave address
1 2
Slave address
1 2
Function code
0 4
Function code
0 4
Input register head address (upper)
0 1
Number of data bytes
0 6
Input register head address (lower)
F 2
Input register data 1 (upper)
1 7
Input register number (higher rank)
0 0
Input register data 1 (lower)
4 A
Input registers number (lower)
0 3
Input register data 2 (upper)
2 8
Error check
[CRC]
Input register data 2 (lower)
5 B
Input register data 3 (upper)
3 9
Input register data 3 (lower)
6 C
Error check
[CRC]
Data of WM1F2-WM1F4 is stored in an order from the high byte.
H 1 7 4 A
WM1F2
WM1F3
H 2 8 5 B
WM1F4
H 3 9 6 C