ABB AC 800M, Руководство по стилю объекта библиотеки

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Parameter for Control Modules and Diagrams Section 3 Parameter Interface
28 3BSE042835-600
• hidden
• by_ref
• constant
• Reverse attribute on data types in diagrams
• Display value attribute on data types in diagrams
Retain shall be used for In and Out parameters in Function Block Types. Whereas
ColdRetain is the normal attribute for operator-settings parameters, such as
operating time measurements, and parameters for operator interaction. Note that the
(cold)retain handling does not support extensible parameters. When declaring a data
type, it should be designed such that it is unaffected if the connected variable of an
instance is declared coldretain/retain by the user.
The nosort attribute can be assigned to a parameter, but this is rarely used.
Parameters that should not be available via the OPC-server, must be given the
attribute
hidden .
The by_ref attribute can only be set for function block parameters with direction In
or Out. This attribute specifies that the parameter value will be passed by reference
instead of the value.
The attribute Constant can be used only for variables.
The reverse attribute works for control modules in diagrams. Split and Join
functions cannot to be used with structured data types containing components with
the reverse attribute. Functions and function blocks cannot handle reverse attributes.
For diagrams there is also a attribute Displayvalue for datatype. If this attribute is set
for a component in a datatype, the value will be shown in online mode for the
connection.
Parameter for Control Modules and Diagrams
In control module and diagram types, a parameter can have the direction In, Out,
In_Out or Unspecified. All of them are passed by reference, which means only a
reference to the actual variable outside the control module is passed to and from the
control module.