Dollar Parameter

[avinash.h@siemens.com]

Hi,
I wanted to understand what does Dollar parameter does???? I went through the help but its still not clear to me. Can someone please help me with that.
We also have function called isDollarDefined();

Thank You.

[jmad]

Hi,

$-Parameters allow the creation of graphical library objects (in WinCC OA we call this a graphical reference). Imagine you have a project representing a street with many cars on it. Typically you make then an icon for a car (car library) but the color should be different for each car.
Instead of making a library object for red car and green car and other cars you just define one reference with a variable parameter defining the color. This dynamic parameter is called a $-Parameter.

E.g. Your car icon is a rectangle then you can define a $-Parameter called $color which takes over the color name (e.g. red) during runtime, when the car enters the street you have on screen.

Technically speeking:

In the initialize event of the rectangle the background color of the rectangel becomes updated.

Engineering in GEDI for the rectangle:
main()
{
this.color($color);
}

Runtime:
$color=red // Rectangle becomes red on screen

[RudiKreiner]

What also might be helpful to know is that you need to assign values to the dollar parameters of your references in the panel that you added the references too.
The property editor of GEDI shows the dollar parameters required by each reference panel when you select it.
It does this somehow by parsing the reference panels to see which dollar parameters it is using.
There is no need to explicitly declare dollar parameters in your reference panels.

[kilianvp]

Runtime:
$color=red // Rectangle becomes red on screen

you cannot assign/modify a dollar parameter durring runtime in CTRL code

[RudiKreiner]

Kilian is right, but if you want the color of your reference panel to change in runtime, here is an example of how to do it.

You can pass the name of a datapoint and, if desired, colors to the reference panel and have the init script set the color.
Here is a simple example with a boolean datapoint

main()
{
dpConnect("work", $DP_NAME);
}

work(string dp_name, bool state)
{
if (state)
this.color = $ON_COLOR;
else
this.color = $OFF_COLOR;
}

[adaneau]

Hi Avinash,

basically a $param is a code placeholder which will be replaced by some value at parsing of your panel.

BR
Alexandre

[lakefalos]

Can't I use dollarSubstitute to modify the dollar parameter. I want to change a dollar parameter $mydp to "$mydp:valve10" I am trying to use it as follows
string groupdp="valve10"
string replaceDollarPar="$mydp:"+groupdp;
dollarSubstitute($mydp, replaceDollarPar);//this subsitutes group back as dollar Parameter.


But it is not working.

[adaneau]

Hi,

dollarSubstitute works only in GEDI as far as I remember.

This is impossible to change value of a $param in a panel already displayed, you will need to open it again with new value ($param are placeholders, not variables).

BR
Alex

[mkerk]

Hi,
dollarSubstitute() works in runtime UI!

You can use dollarSubstitute() to replace the $-Parameter in an expression. BUT you can NOT use this function to replace the value of the $-Parameter itself. This is not possible!!

Below the example from the help:

main()
{
start_motor(makeDynString("$motor:motor17"));
}

start_motor(dyn_string dollars)
{
string dp = dollarSubstitute("$motor + \\".start:_original.._value\\"", dollars);

dpSet(dp, true);
}


As Alexander wrote: the value of the $-Parameter can´t be changed without reloading the Object-Reference!.

Why do you want to change the value of the $-Parameter? what is the use case?

BR;
Mousser.