I am new to modelica and have recently installed the latest version of openmodelica (1.4) on my linux box. Naturally I have a lot of questions. Before asking any I'd like to know whether this is this an acceptable and/or appropriate forum for doing so. There is, supposedly, a mailing list for openmodelica, however, despite repeated efforts I have not been able to join it nor receive any response from its moderators.

Thank you,

Joe Riel

Hello Joe,

you may ask any questions related to modelica, and even something else ;-)

I've been working with openModelica a little bit but then switched to Dymola because of the graphical interface. But maybe I can help you with some of your problems.

Regards

Florian

Thanks, Florian. Because you have used both OpenModelican and Dymola, your feedback should be quite useful. How should I go about debugging an openModelica program? The only thing I know know to do is to pass the program through the compiler (omc). If it runs, great. If it doesn't run, which is quite likely, I get almost no useful information telling me what is wrong. This makes writing a working program extremely difficult. It does return some useful information for syntax errors (but not a lot) however, if the program is syntactically correct but wrong in other ways, such as using a function that is undefined (a typo will do) or gramatically incorrect all I get is a message indicated it didn't build. Is there a way to get more information? Does Dymola do better in this regard?

What is the purpose of the loadModel command used in the scripting language. For some programs I need to use loadModelica(Modelica), presumably to load the Modelica library, however, I don't understand why that is necessary. Shouldn't the existence of an import Modelica.whatever.* statement in the program be sufficient to tell Modelica to load the proper libraries?

Joe

Hi Joe,

debugging in OpenModelica is quite bad. This is one of the reasons why I don't use this implementation of Modelica. There should be a command like check model to verify if a model is syntactically correct or if there is a sufficient number of equations for the system. In Dymola there is something like this. Sometimes the error messages are quite helpful, telling exactly where in the system is something wrong (especially if there is something syntactically wrong).
But if there's an error with the number of equations the you get a hint which sometimes is worse than having no hint. It seems to be very difficult to determine automatically in which component there's an equation to less or to much.

I don't know why you need to explicitely load the Modelica library. Of course, you can build models without using the library but this is an exception. Maybe the Modelica Standard Library consumes a lot of memory and thus, should be only load when necessary.

In Dymola the Library is automatically loaded when then program starts and can be manually unloaded.

Regards

Florian

Hi,

It has gone sometime since this post, but just in case you guys have not seen it yet OpenModelica now has a graphical user interface, MathModelica Lite, provided by MathCore. Please visit the following page if you would like o try it out: http://www.mathcore.com/openmodelica/

Hi,

I am new to modelica and I am keen to learn how to model mechanical/electrical/hydraulic systems. I have Installed Modelica and Mathmodelica Lite. Unfortunately, I cannot even build the 1st model (dc motor) in Mathmodelica Lite!

The symptoms are:

-first, I was able to draw the complete model diagram but the simulate icon would not work

-when loading up the Mathmodelica Lite, the kernel did not load

-I tried re-installing several times

-After this, it gets worse, I can build all of the circuit except when I drag the inertia on to the grid the program terminates

-I tried deleting the original download file, now I cannot even re-register, the email never arrives!


Has anybody had experience with Mathmodelica Lite? I've emailed support@mathcore.com but have not heard from them.

Has anyone found another free GUI for Modelica?

Even though we do not offer support for Lite we have replied to your questions (yesterdays email was actually replied by Daniel within 7 minutes). Please let us know if these emails have reached you or not.

The simulate button is not active in MathModleica Lite (you need System Designer for this), thus it is not supposed to work. To simulate you should use the simulate command in the kernel window (View > Other Windows > Kernel Command or Ctrl+Alt+K).

For the other issues I paste a part of Daniels last answer here for your convinience:

"After taking a closer look at the files you attached to your e-mail I’ve discovered that the Modelica Standard Library seems to be corrupted. The Inertia class is located at Modelica.Mechanics and not Modelica.Mechanics.Rotational for instance. The library is a part of OpenModelica and to solve this issue you need to re- install OpenModelica. After you’ve done this you will also have to update your own models that are using the Inertia class as they are referring to a class that does not exist."

Hope this fixes your problems, and don't forget to let us know if our answers have reached you or not.