0X06) Write Single Register; 0X08) Diagnostics - Hitachi HX-RIO3 Series User Manual

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6.2.6. 6 (0x06) Write Single Register

This function code is used to write a single holding register in a remote device. Therefore, register numbered
1 is addressed as 0. The normal response is an echo of the request, returned after the register contents have
been written.
- In case of address 0x0800 output register value: 0x0000 changes to 0x1122.

6.2.7. 8 (0x08) Diagnostics

MODBUS function code 08 provides a series of tests for checking the communication system between a
client (Master) device and a server (Slave), or for checking various internal error conditions within a server.
The function uses a two–byte sub-function code field in the query to define the type of test to be performed.
The server echoes both the function code and sub-function code in a normal response. Some of the
diagnostics cause data to be returned from the remote device in the data field of a normal response.
• Request
Field name
Function Code
Register Address Hi
Register Address Lo
Register Value Hi
Register Value Lo
• Response
Field name
Function Code
Register Address Hi
Register Address Lo
Register Value Hi
Register Value Lo
• Request
Field name
Function Code
Sub-Function Hi
Sub-Function Lo
Data Hi
Data Lo
• Response
Field name
Function Code
Sub-Function Hi
Sub-Function Lo
Data Hi
Data Lo
Example
0x06
0x08
0x00
0x11
0x22
Example
0x06
0x08
0x00
0x11
0x22
Example
0x08
0x00
0x00
0x11
0x22
Example
0x08
0x00
0x00
0x11
0x22
HX-RIO3 Series