Diagnostics (Fc: 08); Return Query Data (Sub-Function Code: 00) - Mitsubishi QJ71MB91 User Manual

4
MODBUS(R) STANDARD FUNCTIONS

4.11 Diagnostics (FC: 08)

Executes the various diagnostics and checks the QJ71MB91 status and communication
status.

4.11.1 Return query data (sub-function code: 00)

Returns the contents of the request message without change.
Used to check if the network or the target device is operating normally. (Loopback test)
(1) Request message format (Master
(2) Response message format (Slave
4
- 25 4.11 Diagnostics (FC: 08)
4.11.1 Return query data (sub-function code: 00)
Function code
Sub-function code
Sub-function code
Function
(0000
code
(08 )
H
(H)
Figure 4.28 Return query data (Request message)
(When completed normally)
The slave returns the request message received from the master without change.
(When completed with an error)
Function code
Data
Function Exception
code* 1
code
(88 )
H
Figure 4.29 Return query data (Exception message)
* 1 Exception and error codes are stored in the buffer memory in the case of error completion.
Refer to the following for storage location, confirmation methods, and detailed contents.
Section 11.4
Slave)
Data
Arbitrary data
)
H
(L)
Master)