Operator LinkParamTranslator

This operator offers read or write access to the properties of the connected link. Write access may trigger secondary parameter updates via write actions.

The benefit of this operator is that it enables changing link properties via other operators of the library Parameters. Additionally, you may use this operator to change other module parameters when a link parameter changes. For that purpose you can define write actions. You can also use this operator to fix link properties and enforce dependencies between several link properties.

The link format of the output O strictly follows the format of the input I. The module parameters reflect the current status of the link properties at the port I. You may change the module parameters from Read (default) to Write. The mode Read means that the corresponding link property is read-only. This way the operator performs like the operator LinkProperties. If a parameter is set to Write, this parameter can be set. In that case, the parameter value is propagated to the corresponding link property. This has the additional effect, that the corresponding link property at the output port O cannot be edited any more, which is useful for selectively freezing link properties. Additionally, the corresponding link property from an input connection is not propagated to the property of I and O any more. In Write mode, the link property parameter can be edited even when the same property of a connected input link cannot be edited. In that case an error on the input link may show up indicating that the format of an attached previous module doesn't match to the format of the LinkParamTranslator instance.

In the parameter WriteAction you define what happens when link properties change. The parameter Activate activates the write actions defined in WriteAction:

  • If Activate is set to No, then parameters which have the access flag Write may still be changed but no write action is executed. As any link property is a static parameter, the possible write targets must be static, too.
  • If the write target is a parameter of the own module, then the addressed module parameter may have the mode Read or Write.
  • If the parameter has the mode Read, the write action may be used to enforce certain rules on the link properties.

Write actions are composed of one or several equations. If you define more than one equation, separate the equations via semicolon. On the left-hand side of these equations you define which parameter of which module receives the result of the calculation. Use the notation this when referencing a parameter of this module. As soon as the link properties are changed either because of an update of the incoming link or write access to a parameter of this module, the formula(s) on the right-hand side of the equation(s) you defined in parameter WriteAction is/are carried out and the result(s) is/are forwarded to the parameter(s) specified on the left-hand side of the equation(s). As with the left-hand side you can reference parameters of this module using the notation this.

Example:

${this.MaxImgWidth} = (${this.MaxImgWidth} <= 1024) ? ${this.MaxImgWidth} : 1024;

The formula can refer to values of static module parameters anywhere in the design. The formula cannot only incorporate the values of parameters, but also specific properties of parameters, such as minimal value, maximal value, step size, or the numerical value of enumeration items.

[Tip]

Formula syntax: mathematical operations

The syntax complies to the GenICam API standard in version 2.0. The allowed formula elements are identical with the formula elements defined in the GenICam standard:

Basic operations:
() Brackets
+ - * / Addition, subtraction, multiplication, division
% Remainder
** Power
& | ^ ~ Bitwise: and / or / xor / not
<> = > < <= >= Logical relations: not equal / equal / greater / less / less or equal / greater or equal
&& || Logical and / logical or
<< >> Shift left / shift right

Table 41. Basic operations


Conditional operator

<condition> ? <true_expr> : <false_expr>

Example:

${target.Value} = (${this.BitWidth} > 8) ? 2 : 1;

Functions:
SGN(x) Returns sign of x. Returns +1 for positive argument and -1 for negative argument.
NEG(x) Swaps sign of x.
ABS(x) Returns absolute value of x.
SQRT(x) Returns square root of x.
TRUNC(x) Truncates x, which means returning the nearest integral value that is not larger in magnitude than x.
FLOOR(x) Rounds downward, returning the largest integral value that is not greater than x.
CEIL(x) Rounds upward, returning the smallest integral value that is not less than x.
ROUND(x,precision) Rounds x to the number of decimal fractional digits given by precision, with halfway cases rounded away from zero.
SIN(x) Returns sine of an angle of x radians.
COS(x) Returns cosine of an angle of x radians.
TAN(x) Returns the tangent of an angle of x radians.
ASIN(x) Returns the principal value of the arc sine of x, expressed in radians.
ACOS(x) Returns the principal value of the arc cosine of x, expressed in radians.
ATAN(x) Returns the principal value of the arc tangent of x, expressed in radians.
EXP(x) Returns the base-e exponential function of x, which is e raised to the power x: ex.
LN(x) Returns the natural logarithm of x. The natural logarithm is the base-e logarithm: the inverse of the natural exponential function (exp).
LG(x) Returns the common (base-10) logarithm of x.
E() Returns Euler's number, 2.7182818284590451.
PI() Returns circle constant, 3.1415926535897931.

Table 42. Functions


Example:

${target.Value} = NEG(${this.Parallelism})

[Tip]

Paths to parameters

To access an operator parameter any place within your design, you need to provide the path to this parameter in your formula.

For access to an operator's parameter, use the following construct:

PathToModule: Here, you define the relative path to the operator whose parameter you want to access. The path is relative to the hierarchical level the translation operator itself is located. You also define the name of the accessed operator. Use a slash as hierarchy separator.

Module: Name of the module.

As name for the translation operator instance itself, use the name this.

[Important] Keep your modules independent

It is not allowed to define a path towards a hierarchical level higher than the hierarchical level the translation operator is located at. This rule follows the logic that a hierarchical module is not allowed to know anything about the environment it is instantiated in, because only in this case it can be used as a freely relocatable and replicable module.

[Tip]

Access to parameter properties

The formulas cannot only incorporate the values of parameters, but also specific properties of parameters, such as minimal value, maximal value, or step size:

  • ${PathToModule/Module.ParamName.From} or ${PathToModule/Module.ParamName.Min}: the minimal valid value of the parameter PathToModule/Module.ParamName.
  • ${PathToModule/Module.ParamName.To} or ${ PathToModule/Module.ParamName.Max}: the maximum valid value of the parameter PathToModule/Module.ParamName.
  • ${PathToModule/Module.ParamName.Inc}: increment (step size) between two valid values of the parameter PathToModule/Module.ParamName.
  • ${PathToModule/Module.ParamName.Enum("EnumName")}: integer value of the enumeration name EnumName.
[Tip]

Syntax for write access equations

You define the equations for write actions in the parameter WriteAction. They have the following syntax:

Here, you can define multiple equations for multiple target parameters. Use a semicolon as separator between the individual equations.

this refers to the translation operator instance itself.

You find a general introduction into the library Parameters in Library Parameters.

I/O Properties

Property Value
Operator Type O
Input Link I, Image data input
Output Link O, Image data output

Supported Link Format

Link Parameter Input Link I Output Link O
Bit Width [1, 64]1 As I
Arithmetic {Unsigned, signed} As I
Parallelism Any As I
Kernel Columns Any As I
Kernel Rows Any As I
Img Protocol {VALT_IMAGE2D, VALT_LINE1D, VALT_PIXEL0D, VALT_SIGNAL} As I
Color Format Any As I
Color Flavor Any As I
Max. Img Width Any As I
Max. Img Height Any As I

1

The range of the input bit width is [1, 64]. For signed inputs, the range is [2, 64]. For unsigned color inputs, the range is [3, 63] and for signed color, the range is [6, 63].

Parameters

Status
Type static read (although the GUI displays write) parameter
Default None
Range OK or an error message occurs

Displays the error status. If the parameter Activate is set to Yes, the other module parameters are checked. This parameter displays the result of this check, i.e., either OK or an error message occurs.

This parameter is not part of the final applet.

Protocol
Type static write parameter
Default VALT_IMAGE2D
Range {VALT_IMAGE2D,VALT_LINE1D,VALT_PIXEL0D,VALT_SIGNAL}

Allows access to the link property Protocol. Possible values are VALT_IMAGE2D,VALT_LINE1D,VALT_PIXEL0D,VALT_SIGNAL.

ColorFormat
Type static write parameter
Default VAF_GRAY
Range {VAF_GRAY,VAF_COLOR,VAF_NONE,VAF_UNDEFINED}

Allows access to the link property ColorFormat. Possible values are VAF_GRAY,VAF_COLOR,VAF_NONE,VAF_UNDEFINED.

ColorFlavor
Type static write parameter
Default FL_NONE
Range {FL_NONE,FL_RGB,FL_HSI,FL_YUV,FL_LAB,FL_XYZ,FL_HSL,FL_HSV,FL_YCrCb}

Allows access to the link property ColorFlavor. Possible values are FL_NONE, FL_RGB, FL_HSI, FL_YUV, FL_LAB, FL_XYZ, FL_HSL, FL_HSV, FL_YCrCb.

Arithmetic
Type static write parameter
Default UNSIGNED
Range {SIGNED, UNSIGNED}

Allows access to the link property Arithmetic. Possible values are SIGNED and UNSIGNED.

BitWidth
Type static write parameter
Default 1
Range

Allows access to the link property BitWidth.

Parallelism
Type static write parameter
Default 1
Range

Allows access to the link property Parallelism.

KernelRows
Type static write parameter
Default 1
Range

Allows access to the link property KernelRows.

KernelColumns
Type static write parameter
Default 1
Range

Allows access to the link property KernelColumns.

MaxImgWidth
Type static write parameter
Default 1024
Range

Allows access to the link property MaxImgWidth.

MaxImgHeight
Type static write parameter
Default 1024
Range

Allows access to the link property MaxImgHeight.

WriteAction
Type static write parameter
Default
Range

Definition of equations for translation during write access to a link property parameter.

Activate
Type dynamic write parameter
Default No
Range {No, Yes}

Yes = Access to referenced parameters via write equations in WriteAction is activated.

No = Access to referenced parameters via write equations is de-activated and the parameter Status is disabled.

Examples of Use

The use of operator LinkParamTranslator is shown in the following examples: