Eaton SWIRE-GW-MB, Manual, Page: 53 / 67

MODBUS diagnostic functions
(0x08)
49
07/09 MN03407002Z-EN
MODBUS diagnostic
functions (0x08) Diagnostic functions are used to test MODBUS RTU
communications. These functions are used with a separate
function code (0x08). With additional sub-function codes
various diagnostic function codes can be applied to test
communications. The MODBUS message for diagnostic
functions has the following structure:
Request message
Response message
The MODBUS RTU gateway supports the following MODBUS
diagnostic functions:
0x00 Return Query Data
With this command the SWIRE-GW-MB returns the message
sent by the MODBUS master.
0x01 Restart Communications Option
With this command the MODBUS port of the SWIRE-GW-MB
is restarted. If the gateway is in Listen Only state, it is taken
out of this state. With additional code 0xFF in data byte
D
high,res
the error states are reset in addition. If power is
interrupted, the error counters are reset to zero.
0x02 Return Diagnostic Register
The SWIRE-GW-MB does not support diagnostic code 0x02.
It responds to this message with a zero.
ID 0x08 FC
high
FC
low
D
high,req
D
low,req
CRC
low,req
CRC
high,req
ID 0x08 FC
high
FC
low
D
high,res
D
low,res
CRC
low,res
CRC
high,res
0x08 Diagnostics
FC Function code of diagnostic function
D
req
Data field of request message, which can contain
additional data
D
res
Data field of response message, which can contain
return values for the requested diagnostic function