Manual

48 VEGACOM 557 Modbus
Diagnostic message in ASCII mode
Function code 08 (diagnostics) enables diagnostics of the Modbus-participants through the
Modbus-Master. VEGACOM 557 supports the Diagnostic Code 0x0000 (return of the data). In
the field "Diagnostic Data“ any, approved data can be entered, which are returned unchanged
from a functioning VEGACOM 557.
Function 08 is implemented in the same manner for both VEGAMET and VEGALOG.
Example of a diagnostic telegram:
The Modbus participant with the Slave address 1 shall confirm the diagnostic data 0xA5,
0x37.
Start
Slave
address
Function
code
Diagnostic
Code
Diagnostic
Data
Error
Check
End
No. of
bytes
Value
range
Meaning
Structure of the diagnostic function from Modbus master to VEGACOM 557
ASCII enquiry telegram diagnostic (function code 08)
12 2
4422
: 1 .. 247 08
0 0 ... 65.535 LRC CR LF
No. of
bytes
Value
range
Meaning
Structure of the confirmation from VEGACOM 557 to Modbus master
ASCII confirmation telegram diagnostic (function code 08)
Data transmission with Modbus ASCII
:0108
0000 A537 XXCRLF
Start
Slave
address
Function
code
Diagnostic
Code
Diagnostic
Data
Error
Check
End
12 2
4422
: 1 .. 247 08
0 0 ... 65.535 LRC CR LF
:0108
0000 A537 XXCRLF