buildModel() fails with 'ModelicaSystem' object has no attribute 'buildModel'

[Michael Wetter]

Hi

I like to use a Modelica block, set its parameters and simulate it while assigning its inputs from a csv file. Running the commands below, which are from ​https://www.openmodelica.org/doc/OpenModelicaUsersGuide/latest/ompython.html#enhanced-ompython-features, gives the shown error.

>>> from OMPython import OMCSessionZMQ
>>> omc = OMCSessionZMQ()
2020-03-12 15:58:29,708 - OMPython - INFO - OMC Server is up and running at file:////tmp/openmodelica.mwetter.port.b2a371262e6c4fb182a2e58d04ac0dee pid=49441
>>> model_path=omc.sendExpression("getInstallationDirectoryPath()") + "/share/doc/omc/testmodels/"
>>> from OMPython import ModelicaSystem
>>> mod=ModelicaSystem(model_path + "BouncingBall.mo","BouncingBall")
2020-03-12 15:59:14,981 - OMPython - INFO - OMC Server is up and running at file:////tmp/openmodelica.mwetter.port.f6bfd8fa2b0044b5a13ab273c9613b4c pid=49446
>>> mod.buildModel()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'ModelicaSystem' object has no attribute 'buildModel'

Is such a functionality still supported? If not, is there a way to realize this in omc? I tried

import shutil
import os
from OMPython import OMCSessionZMQ

model="Buildings.Controls.OBC.ASHRAE.G36_PR1.AHUs.SingleZone.VAV.SetPoints.Supply"
parameters="(yHeaMax=0.7, yMin=0.3, TSupSetMax=303.15, TSupSetMin=289.15)"
omc = OMCSessionZMQ()
omc.sendExpression("loadModel(Buildings)")
omc.sendExpression("simulate({}, startTime=0, stopTime=3600, simflags=\"-csvInput reference_input.csv\", outputFormat=\"csv\")".format(model))

with reference_input.csv

time, uHea, uCoo, TZonSet, TZon, TOut, uFan
0, 1, 1, 293.15, 293.15, 283.15, 0
3600, 1, 1, 293.15, 293.15, 283.15, 0

but uHea is always zero. Adding a terminating comma as proposed in ​https://openmodelica.org/forum/default-topic/2627-csvinput-usage-and-input-file-format#p8935 won't help.

Moreover, I have not found a documentation for how to set parameters in the block Supply, hence the attempt with ModelicaSystem which appears to provide this functionality

[Michael Wetter]

Do you have an estimate for when this will be corrected? Please advise so I can plan implementing a possible work-around.

[Adrian Pop]

How did you installed OMPython? Install it with:
python -m pip install -U https://github.com/OpenModelica/OMPython/archive/master.zip
and you will have mod.buildModel() method.

I will check the other stuff now.

[Michael Wetter]

I must have had an old version of OMPython installed. I don't recall having it installed with pip, so it may have come from a deb package.

Running your pip command solves the problem and the example now works with version

$ python3 -m pip freeze | grep OM
OMPython==3.1.2

Thanks.

[Adrian Pop]

Don't close this yet as the reading of reference_input.csv doesn't work properly it seems, uHea is zero during simulation and should be one. Strangely the other ones are fine as far as I could tell so it seems like a weird bug.

Also, I will open some ticket for some other usability issues:

• make it possible to use several override flags as the user cannot use it because OMPython does already
• support outputFormat for OMPython simulation command