Enable ViewFinder on Canon EOS 2000D

[jamaaar]

I have a CANON EOS 2000D.

I have tried the following implementation in canon.py:

def eos_init_viewfinder(self):
    ptp = Container(
        OperationCode='EOSInitiateViewfinder',
        SessionID=self._session,
        TransactionID=self._transaction,
        Parameter=[]
    )
    return self.mesg(ptp)

This returns a SessionNotOpen ResponseCode.
Can you give an example, how I can activate and deactivate the viewfinder?

I have also tried to get a viewfinder image. I have used the following short script.

camera = PTPy()
with camera.session():
    print('hello')
    result = camera.eos_get_viewfinder_image()
    print('hello')

I set a breakpoint at the first print('hello'). Then I enable the viewfinder at the camera itself. Then I let the program continue.
In the result the Data variable is empty.
Is the implementation missing?

I have also tried to get and set the parameter EVFMode=0xD1B1. I have had no success.
Can you provide more examples on how to set or get CANON specific properties?

Sorry for the noobish questions. I have no experience with CANON PTP.

Thanks for your help.