smoothing steps in input signal

Hi everybody,

i am relativly new to matlab and i have the following problem:

My input signal has steps that are causing problems in my process. That is why i want to smooth it with a matlab function block. Everytime i have a step (up or down) the function should have a continous S-formed output, comparable to logistic function (see picture below). I know convolution is an option, but i dont know how to realise it via matlab.

can anyone help me please? Thanks in advance!