368 Application Examples
WAGO-I/O-SYSTEM 750
750-880, 750-880/025-000 ETHERNET Programmable Fieldbus Controller
Manual
Version 1.0.1
Example of the MODBUS Addressing
In the case of SCADA Software Lookout from National Instruments the
MODBUS function codes are used with a 6 digit coding, whereby the first digit
represents the MODBUS table (0, 1, 3 or 4) and implicit the function code (see
following table):
Table 411: MODBUS table and function codes
MODBUS table
MODBUS function code
0 FC1
or
FC15
Reading of input bits or
writing of several output bits
1
FC2
Reading of several input bits
3 FC4
or
FC 16
Reading of several input registers or
writing of several output registers
4
FC3
Reading of several input registers
The following five digits specify the channel number (beginning with 1) of the
consecutively numbered digital or analog input and/or output channels.
Examples:
•
Reading/writing the first digital input:
i.e. 0 0000 1
•
Reading/writing the second analog input:
i.e. 3 0000 2
Application Example:
Thus, the digital input channel 2 of the above node "Measuring data" can be read
out with the input: "Measuring data. 0 0000 2".
Figure 81: Example SCADA software with MODBUS driver
Information
Additional Information
Please refer to the respective SCADA product manual for a detailed description of
the particular software operation.
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Adapt the addressing of the SCADA
software to the process image of the node
Hub
ETHERNET TCP/IP
MODBUS protocol
ETHERNET
adapter
Exemplary node "Measuring data"
