ABB AC 800M

Section 3 Parameter Interface Data Type
3BSE042835-600 27
Recommendations for the following properties will be presented:
• Name on page 33
• Data Type on page 27
• Attributes on page 27
• Parameter for Control Modules and Diagrams on page 28
• Parameter for Function Blocks on page 30
• FD Port on page 30
• Initial value on page 31
• Description on page 34
Data Type
It is recommended to avoid structured data types in Function Block Types, since it is
not possible to connect the components of a structured data type directly to other
function blocks.
If a component of a structured parameter is connected to another Function Block in
FBDs, this must be made via a local variable. However, this kind of connections
between two function blocks will not appear graphically, even though they are in
fact connected.
When using the Diagram editor, a structured parameter component may be
connected to an object, using that component data type by directly addressing it as
struct.component. For example, a variable of type real can be connected to the
value component of an object parameter of type RealIO.
Attributes
Control modules and diagrams do not have attributes on their parameters, (only on
variables) since no local copy of the connected variable is made.
For function blocks the entries of the attribute column can be group into three
categories:
• retain or cold retain
• nosort