It is my understanding that you are trying to find the number of samples based on the Solver sampling time of the Simulink model. You would like to get this sample time from what is set in the model, rather than fixing it to particular value.
What you can do is:
1. Get the sample time of model using the function "get_param". This returns a character array.
2. Convert it to a numeric value and use it in the code.
Your code might look similar to the below piece of code:
SampleTime = str2num(get_param(<Model Name>,'FixedStep'));
Use the variable "SampleTime" in place of 0.00005.
Hope this helps!