Hitachi EH-150 Series - Page 108

Chapter 6 Communication Mode
6 - 66
Modbus Slave
 Function code 0x03 (Read Holding Registers)
For EH-SIO, this function code means “Read status of internal output (WR)”. Broadcasting is not supported.
(1) Query
The start address of the internal output (WR) and the number of internal outputs to be read are specified in the
query.
« Note »
A start address should specify I/O number of WR. (For WRF000, the address is specified as HF000.)
(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 WR range, exception response will be returned.
(3) Example
Read the status of WR9A02-WR9A03 (2 words) in the slave 10.
Query
Response
Field name
Example
(HEX)
Field name
Example
(HEX)
Slave address
0 A
Slave address
0 A
Function code
0 3
Function code
0 3
Holding register head address (upper)
9 A
Number of data bytes
0 4
Holding register head address (lower)
0 2
Holding register data 1 (upper)
4 9
Holding registers number (upper)
0 0
Holding register data 1 (lower)
2 A
Holding registers number (lower)
0 2
Holding register data 2 (upper)
C 1
Error check
[CRC]
Holding register data 2 (lower)
F 5
Error check
[CRC]
Data of WR9A02-WR9A03 is stored in an order from the high byte.
H 4 9 2 A
WR9A02
WR9A03
H C 1 F 5