Re: [TRNSYS-users] type 9 problem

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

Constanze,
  TRNSYS should accept any time step for the data file. You need to
make sure that your data file time step is at least as big as your
simulation times step. In other words you cannot run a simulation time
step of 1 hour and a data reading time step of 5 minutes. The second
issue may be that a time step of 1/12 results in an infinitely repeating
decimal (0.08333333...) and when you enter 0.0833 for the fourth
parameter of Type9, TRNSYS interprets this to mean 0.0833000. After a few
time steps the simulation starts running into problems of the data file
and the simulation time step not matching up. One solution is that you
can change the fourth parameter from units of "hours" to units
of "string" and define a variable called "DataStep."
You then need to add an equation to your input file that defines DataStep
= 1/12. In that way, the TRNSYS engine will have much more precision and
there will not be as much mismatch between the simulation and data
reading time steps. I should mention also that Stefan is correct that the
safest simulation and data reading time steps have the form 1/(2^n)
because those never result in repeating decimals. 

  The second problem that you describe (Using 1 hr (to see if the
type works) I get the error message that the system is not able to read
the file correctly) must be specific to the data file and setup of Type9.
If you would like to send me your *.tpf file and the data file, I can
take a look at it for you.
Cheers,
 David
 

At 00:47 6/1/2006, Constanze.Bongs@csiro.au wrote:

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Hi,

 

I am new to using TRNSYS and have run across the following problem which I could not resolve using the manual or the mailing list archives. It is probably really easy but I would be very happy if someone could give me a ?helping hand?.

 

I want TRNSYS to read data (temperatures and relative humidity) from an excel file and use that data as input to a building model. The data in the sheet is taken at time steps of  5 minutes. I tried using TYPE 9 to read it.  However, when I try running the simulation (or Type 9 separately) I get the following error messages:

1.) The system does not seem to allow me to input data time steps of less than 1 hour into parameter 4 (time interval of data) ? although it should if I am well informed. I tried to use hrs as unit and filled in 1/12 or 0,0833 but still the same problem occurred. If I set it back at 1 hr it does not give me the error message any more, but that does not make sense with the data I want to use.

2.) Using 1 hr (to see if the type works) I get the error message that the system is not able to read the file correctly. I inserted the path to the file under external files (and under files in the window that opens as I click on information). I checked the deck file and it gives me the right path to the excel sheet. I also checked the excel sheet but can find no error in the sheet. However, I cannot get TRNSYS to run the simulation (type 9) and read the file.

 

Well, hope someone can help.

 

Cheers,

 

Constanze

 

 

-------------------------------------------------------------

Constanze Bongs

CSIRO Division of Energy Technology

Constanze.Bongs@csiro.au

Ph: 02 4960 6104

fax: 02 4960 6111

-------------------------------------------------------------

 
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