simulation slow down when connecting model with OPC function

I am using VVVF_3PHASE_IM model available in add on file exchange. I am trying to interface the MATLAB model with Seimens TIA portal with the help of OPC server connection . Communication is established and read/Write data is happening fine , but the expected output and simulation time at MATLAB end is very low.

The output values that I am getting are varying rapidly .

For example if I am feeding the reference feed as 1000 rpm , it continously varies from at hardly reaches the 1000 RPM value.

I tried to reduce the simulation time value by changing the sample time value in solver configuration and powerGUI block , but it is again effecting the output values.

Is there any possible solution that I get the steady state output value in realtime simulation time ?

I am using MATLAB 2020a and OPC tool box version 5.0.