Re: [TRNSYS-users] problems creating a new type

[David Bradley <bradley@tess-inc.com>]

Marijke,

> 1/I
> want to call the Psychrometrics - subroutine that is already available in
> Trnsys from my dll. 
> I found some info on how to do this in the Manuel's Programmer's guide
> but it is still unclear to 
> me where in the Fortran-file i have to put these lines. I have the
> temperature and relative humidity 
> of the air as inputs but i want to calculate the wet bulb temperature and
> use it in my calculations
> within the dll. How should i do this?

there should be no difference in the way that your Type (in an external
DLL) calls the psychrometrics() routine and the way that a standard Type
(in TRNDll.dll) calls the psychrometrics() routine. The two basic
arguments required by psychrometrics() are a mode switch to tell the
routine what property data you are providing and then an array that
contains that data and some space for psychrometrics to fill in the rest.
The double precision array is usually called PSYDAT() and is dimensioned
to 7 spots. One of the clearest examples of callng psychrometrics is in
Type33:

C       SET UP ARRAY PSYDAT TO GIVE INFO TO SUBROUTINE PSYCH
100      PSYDAT(1) = PATM
                PSYDAT(2) = TDRY
                PSYDAT(3) = TWET
                PSYDAT(4) = RELHUM
                PSYDAT(5) = TDEW
                PSYDAT(6) = HUMRAT
                PSYDAT(7) = ENTHAL
 
C       DO NOT PRINT ERROR WARNINGS ON THE FIRST CALL
                CALL PSYCHROMETRICS(TIME,INFO,1,MODE,WBMODE,PSYDAT,0,STATUS,*101)
                CALL LINKCK('TYPE 33','PSYCHROMETRICS',1,99)
101      CONTINUE

C       GET INFO FROM PSYCH
                PATM = PSYDAT(1)
                TDRY = PSYDAT(2)
                TWET = PSYDAT(3)
                RELHUM = PSYDAT(4)
                TDEW = PSYDAT(5)
                HUMRAT = PSYDAT(6)
                ENTHAL = PSYDAT(7)
                RHOWM = PSYDAT(8)
                RHOWA = PSYDAT(9)

> 2/My second question is that i need to call an external file from the dll
> to choose in that file appropriate 
> values according to an input value calculated within the dll (like
> chosing a value from a table). I think 
> calling a dynamic data can be a good way to do this. Does anyone know how
> this works and where i
> have to put the necessary lines in my
> fortran-file?

a call to DynamicData is useful if you need the information in your
external file to be interpolated. If that is the case, then there should
be some information in the 08 Programmer's Guide manual on how to call
DynamicData. There are also some good examples again in the code; like
with the psychrometrics() call, there is no difference between a call to
DynamicData() in the TRNDll.dll and in an external DLL. You might look at
Type71 for an example:

C    USE THE DATA SUBROUTINE TO INTERPOLATE TO FIND THE IAM FOR BEAM RADIATION
        X(1)=THETAL
        NXJ(1)=NXDATAL
        X(2)=THETAT
        NXJ(2)=NXDATAT
        CALL DYNAMICDATA(LUDATA1,2,NXJ,1,X,Y,INFO,*821)
        CALL LINKCK('TYPE71','DYNAMICDATA  ',1,99)
821     XKATB=Y(1)

One warning I might give is that when you are dealing with data
files that are read by external DLLs, you have to make sure that both the
TRNDll.dll and the external DLL are set to the same configuration
(release or debug). If the configurations do not match then you will get
all sorts of strange errors that will make you crazy.
Cheers,
 David

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Thermal Energy System Specialists (TESS), LLC
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