4. Configuration
125
{attribute 'symbol' := 'write'} the column shows
{attribute 'symbol' := 'readwrite'} the column shows
Data type of the declared variable.
When the data type is a Struct, a button is enabled in
this column. Clicking on the button will allow the
selection of which elements of that struct will be
provided to the OPC Server.
Variable comment, inserted on the POU or GVL where
the variable was declared. To show up as a variable
comment here, the comment must be entered one line
before the variable on the editor, while in text mode, or
in the comment column when in tabular mode.
Table 4-87. Symbol Configuration object screen fields description
When altering the project settings, such as adding or removing variables, it’s necessary to run the
command Build, in order to refresh the list of variables. This command must be executed until the
message in Figure 4-44 disappear. After this, all available variables in the project, whether they are
declared on POUs, GVLs or diagnostics, will be shown here and can be selected. The selected
variables will be available on the OPC Server to be accessed by the Clients.
Figure 4-45. Selecting Variables on the Symbol Configuration
After this procedure, the project must be loaded into a PLC so the variables will be available for
communication with the OPC Server. If the object Symbol Configuration screen is open and any of
the variables, POUs or GVLs selected is changed, its name will appear with the red color. The
situations in which this may happen is when a variable is deleted or the attribute value is modified.
It’s also possible to set which variables will be available on the OPC Server through an attribute
inserted directly on the POUs or GVLs where the variables are declared. When the attribute
{attribute 'symbol'} is present on the variable declaration, and it may be before the definition of the
POU or GVL name, or to each variable individually, these variables are sent directly to the object
Symbol Configuration, with a symbol in the Attribute column. In this case it’s necessary, before
loading the project into the CPU, to run the command Build from within the object Symbol
Configuration.
The valid syntaxes to use the attribute are:
 {attribute 'symbol' := 'none'} – when the attribute value is ‘none’, the variables won’t be
available to the OPC Server and won’t be shown in the object Symbol Configuration screen.
To Next Page
Loading...
General