Technical data

Application examples • 197
Visualization and control using SCADA software
WAGO-I/O-SYSTEM 750
ETHERNET TCP/IP
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:
Input code: MODBUS function code
0FC1 ! read coils Reading of several input bits
1FC2 ! read input discretes Reading of several input bits
3FC3 ! read multiple registers Reading of several input registers
4FC4 ! read input registers Reading of an individual input register
The following five digits specify the channel number of the consecutively
numbered digital or analog input and/or output channels.
Examples:
- Read the first digital input: i.e. 0 0000 1
- Read 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".
Fig. 8-1: Example of user software G012913e
More information
Please refer to the respective SCADA product manual for a detailed description
of the particular software operation.