D301271 1013 - FGEN - multi protocol
10-15
Programming with CODESYS
Global variable list
The creation of a "Global Variable List" is possible, too:
right-click to "APPL → Add object → Global Variable List".
Define the global variables The global variables are also automatically exported when building the
project, if they have been chosen for export in the symbol configuration. (see also Predefined feature
setsFigure 10-1:, page 10-4).
10.3.9 Modbus channels
The communication between Modbus TCP master and Modbus slaves is realized through defined
Modbus channels.
These channels are set in the register-tab "Modbus Slave Channel" using the "Add Channel..." button.
The process data of a slave can then be monitored under
"ModbusTCPSlave I/O Mapping" (see 10.3.11, Reading out the process data, page 10-25)
The Modbus communication channels are defined by:
"Access Type":
Modbus function code, which defines the access method (bit- or word wise, read or write).
"READ Register" or "WRITE Register" →"Offset":
Specification of the start address for the Modbus Slave's register that has to be read or written.
These specifications have to be taken from the slave's Modbus documentation!
Figure 10-14:
Setting the
Modbus chan-
nels, examples
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