Debugging FBD Programs

When debugging Functional Block Diagram (FBD) programs, monitor the output values of variables. These values display using color, numeric, or textual values according to their data type:
  • Output values of Boolean type display using color. The output value color continues to the next input. When the output value is unavailable, Boolean elements remain black. The colors are red when True and blue when False.
    TIP:
    Before monitoring, remove the strings defined for the
    Message True
     and
    Message False
     variable properties for contacts and coils.
  • Output values of SINT, USINT, BYTE, INT, UINT, WORD, DINT, UDINT, DWORD, LINT, ULINT, LWORD, REAL, LREAL, TIME, DATE, and STRING type are display as a numeric or textual value in the variable. When the output is a structure type, the display value is the selected member.
For structure-type variables, display one simple-type field.
When the output value for a numeric or textual value is unavailable, WAIT is displays in the output label. Values also display in the corresponding dictionary instance.
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