WAGO 750-341 Manual page 178

174 • Application examples
Visualization and control using SCADA software
The WAGO ETHERNET fieldbus node provides the required process input
and output values.
Note
With the WAGO OPC server MODBUS/TCP (Item-number 759-311) the
access from a SCADA software to the MODBUS/TCP ETHERNET fieldbus
devices is very simple and comfortable possible.
Attention!
When choosing suitable SCADA software, ensure that it provides a MODBUS
device driver and supports the MODBUS/TCP functions in the coupler.
Visualization programs with MODBUS device drivers are available from i.e.
Wonderware, National Instruments, Think&Do or KEPware Inc., some of
which are available on the Internet as demo versions.
The operation of these programs is very specific.
However, a few essential steps are described to illustrate the way an
application can be developed using a WAGO ETHERNET fieldbus node and
SCADA software in principle.
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Example of the MODBUS function code
In the case of SCADA Software Lookout from National Instruments the
MODBUS function codes are used with a 6 bit coding, whereby the first bit
represents the function code:
The initial prerequisite is that the MODBUS ETHERNET driver has been
loaded and MODBUS ETHERNET has been selected.
Subsequently, the user is requested to enter the IP address for addressing the
fieldbus node.
At this point, some programs allow the user to give the node an alias name,
i.e. to call the node "Measuring data". The node can then be addressed with
this name.
Then, a graphic object can be created, such as a switch (digital) or a
potentiometer (analog).
This object is displayed on the work area and is linked to the desired data
point on the node.
This link is created by entering the node address (IP address or alias name)
of the desired MODBUS function codes (register/bit read/write) and the
MODBUS address of the selected channel.
Entry is, of course, program specific.
Depending on the user software the MODBUS addressing of a bus module
can be represented with 3 or, as in the following example, with 5 digits.
WAGO-I/O-SYSTEM 750
ETHERNET TCP/IP