Changing Value Field Properties
Value fields allow the user to import or export, literal or variable signal input, to and from the component. Value fields include the following types:
Real
Integer
Logical
Complex
Value field properties are adjusted directly in the property form. Simply left-click on the value field to view its properties and content.
Real Value Field Property Form
Appearance:
Display Name: Enter a caption to act as the visible title of the parameter field.
Symbol: Enter a symbolic name for the parameter field, which will be used as a variable name when addressing this parameter within code. Note that this name must be compatible with standard Fortran naming conventions (i.e. it must begin with a non-numeric character, do not include spaces, etc.).
Behaviour:
Condition: Enter an expression (optional) to indicate under what conditions the parameter field is to be enabled. See Expressions Statements and Operators for more details.
Group: Use this property to organize (or group) the display of the fields in the parameter form. All parameter fields that possess the same group name will be grouped together under the group name heading. For example, the image below shows part of an parameter form, where the fields have all been given the same group name (in this case Positive Sequence):
Visibility: Enter an expression (optional) to indicate under what conditions the parameter field is to be visible. See Expressions Statements and Operators for more details.
Data:
Animated: Select True or False. In order to utilize a value parameter field to control animated text label graphics, this property must be set as True. See Animated Graphics for more details.
Content: Select Literal, Constant or Variable. The selection of Content is very important. Please see the following section entitled Value Field Content Types for a complete description of each.
Dimension: Value type parameter fields may be defined as an array. Enter 1 for a scalar value, or larger than 1 to define a signal array. Note that array parameter fields (Dimension > 1) must be set as Variable or Constant. See the Content property above.
Intent: Select whether or not this field is to function as an input or an output parameter. The intent setting is important to ensure well formed Fortran code is generated for this component when the project is built.
Minimum/Maximum Value: Enter the minimum/maximum value limit for this parameter field. If you are unsure of what the minimum limit should be, or it is not important, simply enter -1e+038/1e+038. If a parameter field value is entered outside this range, PSCAD will provide a warning in the Build or Runtime Message Panes upon compilation, as well as graphically indicate on the component that the data is outside the defined range.
Unit: Add a unit (if any) to represent the Target Unit related to this parameter field. The target unit is the presumptive unit to which all entered values in this parameter field will be converted. See Unit System for more details.
Default Value: Use this property to define the default value that will appear in the parameter field when a new component is created. Assume that a user who is not familiar with this component might simply accept your default value for lack of a better value.
Help:
Help Text: Enter a brief statement describing the field. This text will be displayed on the actual input parameter dialog for the component.
Help Mode: Select Append or Overwrite. If Overwrite is selected, only the help text will appear at the bottom of the dialog when the user selects this parameter. If Append is selected, then the prompt text will be appended to the other parameter attribute information displayed.
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Append |
Overwrite |
Value fields are subdivided into: Real, Integer, Logical and Complex types. These types correspond directly to the Fortran data types REAL, INTEGER, LOGICAL and COMPLEX. In PSCAD, value fields can be further categorized into Literal, Constant and Variable content types. PSCAD versions prior to X4 allowed only type Literal and Variable value fields. Seasoned users will remember the use of the Allow Signal Names option in the Value Field dialog: By default, all value fields were Literal, but could be made Variable by selecting this option.
As a direct by-product of the multiple instance modules feature, a third content type was created and dubbed a Constant. A Constant is a hybrid of sorts in that it possesses key properties of the other two content types. For example, a Constant type field cannot be modified during runtime like a Variable, but can accept the name of a previously defined signal, or an actual number (Literal).
A brief description of each content type:
Literal: Literal type value fields will accept only fixed, numeric values. For example: 23, 657.29, -33.8, or -1 are all valid inputs. Literals are defined at build time, and remain fixed throughout the simulation.
Constant: Constant type value fields will accept only fixed input. However, unlike a Literal type, it will also accept a signal name as its value. The signal value must be from a source that is fixed (non-variable). For example: freq, my_signal, out2, as well as all the examples given for a Literal type above. Constants are defined at build time, and remain fixed throughout the simulation. See Multiple Instance Modules for more details on using Constant type value fields.
Variable: Variable type value fields accept both numeric and non-numeric input. Input values may remain fixed, or they can vary throughout the simulation.
