Dear Wireshark-users:
Our Nicaraguan non-profit development organization is in the process of
trying to determine a operator panel periodic freeze. This operator
panel receives instructions from a controller. The operating panel
and controller automate the operations of a 930 kW small hydro
plant that provides electricity to a number of rural towns and
villages.
The representative of the control system in Finland indicates that we
should tap directly into the cable that sends data back and forth between
the AC800M controller and the 235 Operator Panel. This is a special
cable that has a female 9-pin RS-232 plug on one end and an RJ-45 male
plug on the other end. A direct serial connection. How can one
capture Modbus traffic or in other words obtain a trace file from this
serial connection?
The control system representative also says that the software must
support �MODBUS� protocol. When you open the Wireshark main page,
and drop-down the HELP menu, there is a part of the HELP that gives a
list of � 911 protocols and packet types supported by Wireshark�.
On this list we find �MODBUS/TCP� but not �MODBUS�. The
representative from Finland thinks that �MODBUS� is different from
�MODBUS/TCP�, and that we need Wireshark to support the �MODBUS� protocol
to analyze the AC800M-to-Operator Panel traffic. Is Modbus/Tcp
different from Modbus and if so can wireshark capture traffic in the
Modbus protocol or possibly translate from one protocol to the
other?
Thank you for your help,
Cheers,
Niko
- Niko Kozobolidis, P. Eng.
- ATDER-BL
