Unable to change parameter value in SSP

[larsviktorlarsson]

Description

When I change a parameter value in an .ssd file from the python api, it does not have an effect on a certain FMU.

Steps to reproduce the behavior

My python script:

from OMSimulator import SSP as oms_ssp

from OMSimulator import CRef

from OMSimulator import Capi as oms_capi

try:
oms_capi.terminate("model")
except OSError:
pass
try:
oms_capi.delete("model")
except OSError:
pass

oms_model = oms_ssp("ParkerSimPack.ssp")
oms_model.activeVariantName = "D16_auto_stimuli"
oms_model_inst = oms_model.instantiate()

oms_model_inst.setResultFile('D16_auto_stimuli_results.csv')

oms_model_inst.initialize()

oms_model_inst.setValue(CRef("D16_auto_stimuli","interface_model.k_p"),0)

oms_model_inst.simulate()

oms_model_inst.terminate()
oms_model_inst.delete()

Expected behavior

When I plot the results in Matlab i get:

But, the variagble theta should be zero after I have changed the parameter value of k_p to 0. If I simulate in easy-ssp I get (which I expect in OMSimulator as well):

Model

ParkerSimPack.zip

Version and OS

• Version: 'OMSimulator v3.0.0.post103-g53bba5e-win'

• OS: Win11 64 bit

[arun3688]

@larsviktorlarsson i can reproduce the issue, i will debug more and fix the issue

[arun3688]

@larsviktorlarsson I did some debugging and i found few things, the composite model has algebraic loops, due to the following connections

 valve_model.qA -> interface_model.qA.out.y
 valve_model.qB -> interface_model.qB.out.y

And when you set the value, you have to set it before initialization, so it should be

oms_model_inst = oms_model.instantiate()
oms_model_inst.setResultFile('D16_auto_stimuli_results.csv')
oms_model_inst.setValue(CRef("D16_auto_stimuli","interface_model.k_p"),0) // set it before initialize
oms_model_inst.initialize()

But this does not solve the issue, but you can see that parameter value for interface_model.k_p is changed to 0 in the plots. So the change of parameter value works, but it does not produce the desired result according to you and i hope the value k_p is internally has some equations which are dependent on it. But i don't see any connection with interface_model.k_p to other fmu component.
Since i cannot see the model i don't know how these change in value in k_p is affection the simulation results.

Test1:

In the .ssd file , currently the value of k_p is set to 130 and if you directly change in the .ssd file to 0, then you get the correct results as you mentioned

Test 2:

Eliminate the above the two connections and it also produces the desired result.

Test 3:

If you completely eliminate the valve model, then you also get the desired result, You can do that by following

oms_model = oms_ssp("ParkerSimPack.ssp")
oms_model.activeVariantName = "D16_auto_stimuli"
oms_model.delete(CRef('D16_auto_stimuli', 'valve_model')) ## delete the whole valve model from the system
oms_model_inst = oms_model.instantiate()
oms_model_inst.setResultFile('D16_auto_stimuli_results.csv')
oms_model_inst.setValue(CRef("D16_auto_stimuli","interface_model.k_p"),0)
oms_model_inst.initialize()
oms_model_inst.simulate()
oms_model_inst.terminate()
oms_model_inst.delete()