FAQ Overview
Frequently Asked Questions

Our homepage on WWW contains a section of Frequently Asked Questions. This section is updated on a regular basis, and will always contain the most recent problems encountered by our users.

This hjelp help file contains the last FAQ available at the time of release. This file will be updated to reflect the FAQ section on our web wite, with regular intervals. It will also contain other useful tips and articles about Powersim, modelling and software.

1.	Diagram Editing 	-	manipulating the workspace and model building blocks, simulation settings...

2.	Printing	-	printing bitmap pictures, model documentation, text, equations...

3.	Error messages and limits	-	common error messages and what they mean and important limits to Constructor functionality.

4.	Links and data transfers	-	using Constructor with DDE and OLE is not as difficult as you might think.

5.	Advanced modelling issues	-	co-models, arrays, generations, network games and other "beyond the basics" uses of Constructor.

6.	Installation problems	-	issues you may encounter when installing Constructor to your machine or over a network.

7.	Constructor objects	-	manipulating the various objects, including the Command Button add-on.


Diagram Editing

1.	How can I copy a selection in a diagram and paste it as a picture in another application?

2.	Why does the last part of my object text sometimes disappear when I change the zooming of a diagram?

3.	I could not move a selected group of objects in a diagram. Why?

4.	What happens when I use auto reports on array variables?

5.	When I name a variable, the name disappears as soon as I hit the Return key.

6.	If I choose Normalized View for my time graph, everything disappears, including axis, values and titles.

7.	Is there a Powersim Constructor 2.5 editor that allows the user to prepare equations in text mode?

8.	Is there an auto-sizing capability in Powersim Constructor 2.5, which will automatically make all the model windows look nice regardless of the monitor size?

9.	What is the procedure for entering or editing text in a text box when running Powersim Constructor 2.5 under Windows NT 4.0?

Note!	To display the answer to a question, click on it!


How can I copy a selection
How can I copy a selection in a diagram and paste it as a picture in another application?

Answer:

You must copy the selection as an area, which means you must use the right mouse button to mark the selection. Click and hold the right mouse button and drag the cursor across the area you want to copy. Powersim Constructor 2.5 automatically draws a box around the area. Copying is then performed as in any Windows application, using the Edit Copy command of Constructor 2.5 and the paste command of the destination application.


Why does the last part of my object text
Why does the last part of my object text sometimes disappear when I change the zooming of a diagram?

Answer:

Powersim Constructor 2.5 formats text according to 100% scaling of the diagram. Since MS-Windows is not capable of sizing fonts accurately when scaled, text may appear too wide or too narrow when the diagram is zoomed. Normally you may avoid this problem by making the objects containing the text a little larger than seems necessary when zoomed to 100%.


I could not move a selected group
I could not move a selected group of objects in a diagram. Why?

Answer:

When a group of selected variables contains more than one item, at least one of which is a rate directly connected to a flow valve (see left figure below), the selection may be moved only for dropping purposes. This means that the selection may be dropped into a dynamic object (see Adding Variables to Dynamic Objects) but may not be moved to another location in the diagram. When you start to move such a selection, the statusbar (if present) will display: "Selection available for dropping only". If you try to complete the move operation without dropping the selection into a dynamic object, a message box will appear saying: "Attempt to move a selection that was available for dropping only". If you want to move a rate along with other variables, you must include the flow object to which the rate is connected in the selection (see right figure below).

Selection may be moved only for dropping.	Selection may be moved in the diagram


What happens when I use auto reports
What happens when I use auto reports on array variables?

Answer:

When using arrays in combination with auto reports, it is only the values of the first dimension in the array variable that show. To see all values of the array, you may use an array graph or a time table.


When I name a variable
When I name a variable, the name disappears as soon as I hit the Return key.

Answer:

The name is already used by another variable. All variables in a Powersim Constructor 2.5 diagram must have unique names.


If I choose Normalized View
If I choose Normalized View for my time graph, everything disappears, including axis, values and titles.

Answer:

In Normalized View the scaling of each variable is displayed to the left of the time graph. The solution is to make the time graph object larger and/or switch off Labeled Scales in the Define Time Graph dialog box.


Prepare equations in text mode
Is there a Powersim Constructor 2.5 editor that allows the user to prepare equations in text mode?

Answer:

No, there is not. You may view the equations by choosing View Equations from the File menu, but you may not edit equations in that view. You may only edit equations in the CONSTRUCTOR 2.5 diagram, by opening each variable's dialog box.


Is there an auto-sizing capability
Is there an auto-sizing capability in Powersim Constructor 2.5, which will automatically make all the model windows look niceregardless of the monitor size?

Answer:

The different sizes of the Windows desktop depends on the graphic mode that is used, and not the size of the display screen. Typically, people use three different graphic resolutions, 640x480, 800x600, and 1024x768. Here at Powersim we always make sure that our models work OK with the 640x480 resolution, which is the "standard" VGA resolution that all modern PCs support. The check that we go through before releasing a model, is to switch our display to 640x480 mode and position all windows nicely before we save our model. Since this is the lowest resolution, clients can then use the models on higher-resolution screens without problem.


Entering or editing text in a text box
What is the procedure for entering or editing text in a text box when running Powersim Constructor 2.5 under Windows NT 4.0?

Answer:

Unfortunately Windows NT behaves differently than other Windows versions in several ways. A mouse click outside an object cannot be recognized (easily) by an object, for example. We therefore decided to change the functionality of the direct text manipulation in Constructor 2.5.

You must now do the following:

1.	Press Esc to cancel text input.

2.	Press Return to accept text input.

3.	Press Ctrl+Return to enter a line break inside the text.


Printing

1.	Why doesn't my bitmap picture show on a printout?

2.	Why do graphs with light colors turn to black when I print them?

3.	How can I see and/or print a full documentation of my model, including my own documentation of each equation?

4.	Why is my text cut off in the printout?

5.	In Powersim Constructor 2.5, how can I print my model equations?

Note!	To display the answer to a question, click on it!


Why doesn't my bitmap picture
Why doesn't my bitmap picture show on a printout?

Answer:

If your document contains picture objects of type Bitmap, these objects may not show on printouts. To avoid this, follow the recommendation given in Picture Object. For example, if you copy bitmaps from Microsoft Windows Paintbrush, you should clear Options Omit Picture Format.


Why do graphs with light colors
Why do graphs with light colors turn to black when I print them?

Answer:

It is possible that your printer does not distinguish between different color shadings. If you cannot find the solution in the printer setup, try this:

1.	Open the Define Time Graph dialog box.

2.	Choose either the Background or Graph Area button. There you may define the Interior part of the graph.

3.	Choose None in the list for Pattern.

4.	Click your way out with OK.

5.	Try to print again.


How can I see and/or print a full documentation
How can I see and/or print a full documentation of my model, including my own documentation of each equation?

Answer:

1.	Open Format Options.

2.	Select the Equations View category.

3.	Now choose the elements you want to display when you are in the Equations View.

4.	Print the model with documentation by choosing "Equations" or "Diagram and Equations" in the Print dialog box.


Why is my text cut off in the printout?
Why does my model sometimes appear different on paper than it does on the computer screen? In particular, names of variables and information in text boxes are sometimes cut off.

Answer:

Try the following:

1.	Spread the variables out more on the screen to leave room for their names.

2.	You may need to leave a lot of space between items, depending on the resolution of your printer.

3.	Make text boxes larger on the screen to avoid losing some letters during printing.


Print my model equations?
In Powersim Constructor 2.5, how can I print my model equations?Print5>ans

Answer:

You may have turned off Edit in the File Properties Access menu. This excludes printing of Equations. If you turn Edit on again, you will get the possibility to print Equations.


Error messages and limits

1.	What is the current variable limit in Powersim Constructor 2.5?

2.	Is POWERSIM CONSTRUCTOR 2.5 supporting the new 32-bit operating systems?

3.	Is there a memory limitation for the DelayPPL function?

4.	Does POWERSIM CONSTRUCTOR 2.5 set a limit on the number of pages allowed per model, when seen in Diagram view?

Note!	To display the answer to a question, click on it!


What is the current variable limit
What is the current variable limit in Powersim Constructor 2.5?

Answer:

The latest version of Powersim Constructor 2.5, has the following variable limits:

       6,500 variables

       30,000 scalar variables + array elements (old limit: 6,500)

       4,000 array elements per array

Note: Powersim Constructor 2.5 requires Windows 95 or Windows NT to support the new variable limits; it will run under Windows 3.11, but will constrain the total of scalar variables plus array elements to the prior limit of 6,500.


Supporting the new 32-bit operating systems?
Is POWERSIM CONSTRUCTOR 2.5 supporting the new 32-bit operating systems?

Answer:

No, Constructor 2.5 does not support the 32-bit operating systems. It still behaves as a 16-bit application. Therefore, in the Win32 extension to Windows 3.11, CONSTRUCTOR 2.5 is the same as it is under Windows 3.x.


Memory limitation for the DelayPPL function?
Question:

Is there a memory limitation for the DelayPPL function? My model has less than 200 variables but many delay functions. I get the error "Unable to allocate enough memory for the function DelayPPL used by variable XXX." My computer has plenty of free space on the hard drive.

Answer:

You have problably run into a 64K limit for the sum of variable elements and implicit variable elements created by functions that have internal levels. These limits have been increased significantly in Powersim Constructor 2.5.


Limitied number of pages in Diagram View?
Question:

Does POWERSIM CONSTRUCTOR 2.5 set a limit on the number of pages allowed per model, when seen in Diagram view? Does the Portrait or Landscape setting make any difference to the total number of pages?

Answer:

There is a limit to the size of the diagram, but it is determined by the 16-bit coordinate system of Windows, not by CONSTRUCTOR 2.5. This maximum size, divided by the page size, determines the number of pages you can have horizontally and/or vertically.


Links and data transfers

1.	How do I import data using DDE?

2.	Is it possible to open and run a Powersim Constructor 2.5 model from another application, such as Microsoft Excel?

3.	Is it possible to move a large block of data (such as 5000 numbers) into a Powersim Constructor 2.5 array variable using a single command or transfer object?

Note!	To display the answer to a question, click on it!


How do I import data using DDE?

Description:

I tried to import data from a spreadsheet using the DDE object. But the constant that I used as a parameter for the DDE import still has a question mark within it after I have defined the DDE object, and Powersim says "Unable to simulate". What did I do wrong?

Answer:

You must give the constant a default definition, such as 0. The DDE link will update this value anyway.


Is it possible to open and run a model in Excel?
Is it possible to open and run a Powersim Constructor 2.5 model from another application, such as Microsoft Excel?

Answer:

Yes, it is possible, by defining macros in the application you want to use to control Constructor 2.5. Powersim Constructor's User's Guide gives several examples of macros that will open and run Constructor 2.5 models. If these macros run, but do not open Constructor 2.5, make sure the path to  Constructor 2.5 is in your AUTOEXEC.BAT file, as follows:

path=c:\windows;c:\powersim

This will enable the application to locate Powersim.exe.


Is it possible to move a large block of data into an array?
Is it possible to move a large block of data (such as 5000 numbers) into a Powersim Constructor 2.5 array variable using a single command or transfer object?

Answer:

Both the DDE and Archive objects can do this in one operation. You must list all the array elements in the Parameters list and give the data file/DDE reference in the section at the bottom of the definition dialog box. The data must be organized according to the sequence in which you have listed the parameters. For instance, the elements of a two-dimensional array, A, with dimensions i = 1..3 and j = 1..2 will be stored in this  sequence:


Advanced modelling issues

1.	Why do I lose settings saved in a co-model?

2.	Can arrays be used as input parameters to delay functions?

3.	I wish to make sure that a flow runs only in one direction (uniflow). Is this possible with POWERSIM CONSTRUCTOR 2.5?

4.	Why are there no new values being added to my time graph that contains generations?

5.	Why are my model's oscillations amplified?

6.	Is there an easy way to get a model into steady-state?

7.	In a network game, is it possible for one player to finish playing before the entire game is finished, while the other players continue playing?

8.	Is there a way to change the timing of a graph output so it is not delayed by one period?

9.	If I make applications using the Powersim Engine, do I have to choose between 32-bit and 16-bit platforms?

Note!	To display the answer to a question, click on it!


Why do I lose settings saved in a co-model?

Description:

 A main model with a window into a co-model contains a time table. The time table was saved with the Time option Step not equal to the Auto setting. Why does the Step value go back to Auto when I open the main model after having closed it?

Answer:

This happens because Times and Scale settings of dynamic objects are instance data. This means that if one model is used as a co-model by several main models, these options may have different values, which are saved in each main model. The solution to your problem is to make sure that you save t he main model after having edited Times and Scale settings of a co-model object.


Can arrays be used as input parameters to delay functions?

Description:

I tried to use an array variable as an input parameter to a delay function, for example: DELAYPPL(ArrayVar, 5), but then a message box appeared, saying that a scalar was expected. Does it mean you can not pass arrays as input parameters to delay functions?

Answer:

Yes, you can, but you must make use of an index variable to do so. In the example below, the index variable i, declared in the Dimensions part of the definintion of ArrayDelayed, is used as a subscript of ArrayVar. This makes the DELAYPPL function return the delayed values for each element of ArrayVar.


A flow runs only in one direction
I wish to make sure that a flow runs only in one direction (uniflow). Is this possible with POWERSIM CONSTRUCTOR 2.5?

Answer:

In the definition of the flow rate you may use the MAX function, for example, like this: MAX(0, SINWAVE(-5, 5)).


New values being added to time graph
Why are there no new values being added to my time graph that contains generations?

Answer:

What happened is that you have deleted the parameter that contains the values from the latest run. This one has no number (i.e. #8) indicator after the variable name. When you delete this one, you automatically say that you are not interested in any further values for this part icular variable. When used with intention, this might come in handy.


Model oscillations amplified
Why are my model's oscillations amplified?

Description:

I copied a classic model which was supposed to show sustained oscillations. But when I simulated it, the oscillations amplified (increased) rapidly. What is wrong?

Answer:

You might need to reduce the time step or choose a higher-order integration method, such as Runge-Kutta 2, 3, or 4. Both settings are found in the Simulation Setup Dialog box.


Get a model into steady-state
Is there an easy way to get a model into steady-state?

Answer:

The important observation to make, is that in steady-state the sum of the flows connected to each level of the model must be zero. The process our modelers normally use is the following:</p>

1.	Inspect the equations of each level one at a time, and make sure that inflows - outflows are zero for the initial value of the level. If necessary, introduce an expression for the level's initial value in order to make the flows net to zero. </p>

2.	Run the model and make sure it is in steady state (no values change during simulation). </p>

3.	If the model is not in steady state, do the following to identify the source of the instability: </p>

a. Make sure Options Format is set to display auto reports as numbers.

b. Press the pause button and then the play button.

c. Look through the model to find a level where the numeric values for the flows does not net to zero.

d. Fix the problem by changing flow equations or initial value for the level, and go back to 2.</p> </blockquote>

Iterate through these steps as necessary until the model is in steady-state. </p>


Network game
In a network game, is it possible for one player to finish playing before the entire game is finished, while the other players continueplaying?

Answer:

Currently, it is not possible to continue playing after one of the players leaves the game. At the very least, each player has to press the Advance button for each decision period. If it is necessary for a player to "leave" the game, such as when he or she runs out of money, th e game itself must allow the player to continue making decisions, even though the decisions would necessarily be of zero value.


Change the timing of a graph output
Is there a way to change the timing of a graph output so it is not delayed by one period?

Answer:

The time graph object waits until it gets the guaranteed final value at a time step before it draws the graph at that time. The graph would otherwise have to redraw the part between the current time step and the previous step every time the user changes the value in pause mode.

Most other Powersim Constructor 2.5 objects, like array graph, time table, number, and slider/bar update the display up to and including the current step, also in pause mode. The array graph can be used to get the updated va lue in the current time step.


Make applications using the Powersim Engine
If I make applications using the Powersim Engine, do I have to choose between 32-bit and 16-bit platforms?

Answer:

The current version of Powersim Engine behaves identically in the 16-bit and 32-bit version. This should make it easy to make programs for both platforms. In the future we may make extensions to the Engine that will be supported only in the 32-bit environment, however.</p>


Installation problems

1. How can Powersim Constructor be installed over a network?

Answer:

This depends on your license. If you have a site license it is possible to install a master copy to a server, and then do minimal installations from the master to each workstation. This minimal installation only copies system files to the workstation in order to make Video for Windows work properly. It also registers Constructor 2.5 in the registration database, which is necessary because Constructor 2.5 is an OLE server. If you do not have a site license, you must install the full CONSTRUCTOR 2.5 software on each workstation.


Constructor objects

1.	When my simulation stops and I click on the Command Button, it only becomes selected. Why doesn't anything happen?

2.	How can I get the Command Button to open a file using a path? I can only get it to open files in the current directory.

Note!	To display the answer to a question, click on it!


When simulation stops
When my simulation stops and I click on the Command Button, it only becomes selected. Why doesn't anything happen?

Answer:

The Command Button (and other objects that let you interact with the simulation) is only activated during the simulation. If you want to edit it after the simulation ends, you can do so in any of the following ways:

1.	Select the Command Button and press RETURN.

2.	Select the Command Button and use the Edit Define Object command.

3.	Deselect the Command Button and double-click on it.

The above procedures are applicable to other objects as well, such as the Button object.


Command Button
How can I get the Command Button to open a file using a path? I can only get it to open files in the current directory.

Answer:

You must use double backslashes in path names (a single backslash is considered an escape character).  Example: C:\\Models\\Sample.sim