[TRNSYS-users] Message 441

[Diego A. Arias]

Dear Edward,

It is not always clear how to find an appropriate order in which to call 
the components. The kernel recognizes that some components should be 
called at different times during the simulation: for example, during 
each iteration or only when the simulation has converged. Integrators 
and printers (Type25) are some of the components that are only called 
when all of the other types have converged.
The feature in the Studio tries to help, but as I said, this is not a 
trivial thing, and some rules may work sometimes and do not work in 
other simulations.

One of the most important capabilities in TRNSYS is to be able to 
simulate many different kinds of systems. One user's simulations may not 
look anything like another user simulation. Therefore, it is very 
difficult to point out the exact cause of the problem when there are 
many reasons why the simulations may go wrong. What I have seen is that 
the most useful error message is generally the first one, as when 
something goes wrong it usually triggers many other problems.

Best regards,

Diego

Edward Halawa wrote:
> Dear Constanze,
>
> The similar problem you had occurred to my first program using TRNSYS
> 16.0 this week. I was a bit "annoyed" to find out that the cause was
> that the components order is not "optimum". (Version 15 problem stil in
> there in Version 16).
>
> I used as my first program the Solar Water Heating project created when
> you click on the "Solar Hot water System" icon which appeard when you
> create "New" project.
>
> In this project I added a number of new components (forcing functions
> and printers Type 25b-user supplied units). After satisfied with the
> connection I clicked on the "Component Order" to hit the "Optimise
> Components Order". My program worked. However, when I edited again
> (adding more forcing function, changing connection etc), I had your
> experience and my program halt after time 440 hr - Error Message 441
> displayed. It took me one day (!) to see that the problem was because:
> the component order "did not make sense". Pressing "Optimise Components
> Order" button did not optimise the order ! Printers are in the middle,
> radiation processor is near the end of the order (which should be in
> right after the Type 9 and before collector", etc. (Note: I changed Type
> 109 to Type 9 plus Type 16g because I have different format of weather
> data).
>
> After this my prgram worked ... :) :(
>
> Note:
> (1) My solution (checking the Component order or Optimimise it
> "manually") may not work to solve your problem but it's worth trying.
> It's a bit of trial and error ... This may be annoying for a program
> containing large number of components).
> (2) I do not rely much on the "Error Analysis" created by Version 16.0.
> Information is too much but (for most of my first week) I could not
> pinpoint the problem by reading it. For example, when it wrote something
> like "The ouput file may be locked by Microsoft Excel ..." may be not
> the real cause. (I closed Excel and the problem still there). But after
> I deleted altogether Type 25b and replaced it with Type 25a, the problem
> disppeared). 
> (3) "Loading TRNSYS and processing the input files. Please wait ..."
> takes quite long time to disappear.
>
> Regards,
>
>
> ehalawa
>
>
> Constanze.Bongs at csiro.au wrote:
>   
>> Hi,
>>
>> During simulation the following warning occurred:
>> Message 441: The inputs to the listed units have not converged at this
>> timestep. The values of the last iteration will be used to proceed. 
>>
>> As I get this message more than thirty times Trnsys sends an error
>> message and stops the simulation. 
>>
>> I already set the tolerance convergence to 0.5 (from 0.001) and
>> tolerance integration to 0.01 (from 0.001).
>> Can you explain to me what is happening and how I can fix it? Does
>>     
> this
>   
>> mean that the system is too complex to be solved and are the
>>     
> simulation
>   
>> results still useful? Which maximum values for tolerance convergence
>>     
> and
>   
>> tolerance integration still manage to give me reasonable results?
>>
>> Cheers,
>>
>> Constanze
>>
>> _______________________________________________
>> TRNSYS-users mailing list
>> TRNSYS-users at engr.wisc.edu
>> https://www.cae.wisc.edu/mailman/listinfo/trnsys-users
>>   
>>     


-- 

Diego A. Arias
TRNSYS Coordinator
Solar Energy Laboratory
University of Wisconsin - Madison
1500 Engineering Drive
Madison, WI 53706