Hach Sigma 950, Инструкция по эксплуатации инструмента

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122
SCADA-Modbus
®
System Guidelines
950 SCADA-Modbus “No-Response” Troubleshooting Flow Chart (4 of 5)
Use either a protocol analyzer or a
communications program such as Windows
Terminal or Comit running on a PC in place
of the 950 to intercept and verify the Modbus
polling request being sent from the master
device to the 950.
Continued from sheet 3
Is the
Modbus message
being received
?
The problem is in either
the Modbus Master
(polling) device or the
communications media.
Correct problem and then
check for response again.
Does the
Modbus message start
with a colon and end with a
Carriage Return and Line
Feed pair ?
Does the message
address match the
Modbus device address
of the 950 ?
Yes
The first two characters
in the message, after the
colon, denote the
Modbus device address
in Hexadecimal.
No
Either change the
Modbus device
address of the 950 or
change the address in
the Modbus server.
Is the
flow meter
responding
now ?
Congratulations
You've fixed it !
Yes
No
Put the RX and TX
wires back to the way
they were before.
Yes
No
Yes
No
Make a note of the
Modbus message and
then call tech support
to have the
Modbus message
validated.