Specifications

4P357732-1 – 2014.04 Page 16 of 58
2.2 Communication format
2.2.1 Function format
(1) Read Input Registers (0x04)
[Function]
Read values of input registers. The address and the content of input registers are described in
3. Modbus registers
[Query]
The query message specifies the start address of the register and the number of registers. The register
address starts at zero: register 30001 is addressed as 0.
This function can read up to 32 registers in one query.
Here is an example of a request to slave address 1 for reading 3 register values starting from register
31001.
Query
Response
Field
Data
Field
Data
Slave Address
0x01
Slave Address
0x01
Function Code
0x04
Function Code
0x04
Start Address(Upper)
0x03
Data Size(Bytes)
0x06
Start Address(Lower)
0xE8
Data1(Upper)
0xXX
Number of Registers(Upper)
0x00
Data1(Lower)
0xXX
Number of Registers(Lower)
0x03
Data2(Upper)
0xXX
Error Check CRC16(Lower)
0x30
Data2(Lower)
0xXX
Error Check CRC16(Upper)
0x7B
Data3(Upper)
0xXX
Data3(Lower)
0xXX
Error Check CRC16(Lower)
0xXX
Error Check CRC16(Upper)
0xXX