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FnIO MODBUS Adapter NA-9171, NA-9173
FnIO S-Series
Copyright(C) CREVIS Co.,Ltd Support +82-31-899-4599 URL : www.crevis.co.kr
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
Example
RTU
ASCII
ASCII (bus line)
Start of Frame
-
t1-t2-t3
“,”
0x3A
Slave Address
0x07
0x07
“07”
0x30, 0x37
Function Code
0x08
0x08
“08”
0x30, 0x38
Sub-Function Hi
0x00
0x00
“00”
0x30, 0x30
Sub-Function Lo
0x00
0x00
“00”
0x30, 0x30
Data Hi
0x11
0x11
“11”
0x31, 0x31
Data Lo
0x22
0x22
“22”
0x32, 0x32
Error Check (CRC/LRC)
-
0x6C, 0x24
“BE”
0x42, 0x45
End of Frame
-
t1-t2-t3
CR, LF
0x0D, 0xA
Response
Field name
Example
RTU
ASCII
ASCII (bus line)
Start of Frame
-
t1-t2-t3
“,”
0x3A
Slave Address
0x07
0x07
“07”
0x30, 0x37
Function Code
0x08
0x08
“08”
0x30, 0x38
Sub-Function Hi
0x00
0x00
“00”
0x30, 0x30
Sub-Function Lo
0x00
0x00
“00”
0x30, 0x30
Data Hi
0x11
0x11
“11”
0x31, 0x31
Data Lo
0x22
0x22
“22”
0x32, 0x32
Error Check (CRC/LRC)
-
0x6C, 0x24
“BE”
0x42, 0x45
End of Frame
-
t1-t2-t3
CR, LF
0x0D, 0xA
Sub-function 0x0000(0) Return Query Data
The data passed in the request data field is to be returned (looped back) in the response.
The entire response message should be identical to the request.
Sub-function
Data Field (Request)
Data Field (Response)
Description
0x0000(0)
Any
Echo Request Data
Sub-function 0x0001(1) Restart Communications Option
The remote device could be initialized and restarted, and all of its communications event counters are cleared.
Especially, data field 0x55AA makes the remote device to restart with factory default setup of EEPROM.
Sub-function
Data Field (Request)
Data Field (Response)
Description
0x0001(1)
0x0000, 0xFF00
Echo Request Data
Reset
0x0001(1)
0x55AA
Echo Request Data
Reset with Factory Default*
*All expansion slot configuration parameters are cleared.
Sub-function 0x000A(10) Clear Counters and Diagnostic Register
