Hello everyone,
I am a new student and a complete newbie both in matlab (writting .m files also) and simulink.
I want to assign a signal derived from excell file (square shaped signal, uint16, 1Hz, 1s width, changing amplitude) in simulink to a parameter that is one of the parameter in a masked function.
I already managed to get the excel file to a kind of a signal generator with a help from a signalbuilder.m which were build by someone (unknown fellow student years before me).
Usually I change manually  the parameter in masked function (function made by someone else and it is not to be changed) by double clicking the block or right click and choose mask parameters (before I hit the play/run button). 
Now I want/must change the parameter automatically according to the signal I have mentioned before.
After searching the help section I get the set_param command, but it is still not very clear to me how to achieve what I want. 
If a run the simulink simulation and I want that the parameter to change accordingly to the signal during the simulation, how/ what I suppose to do? No one whom I know seems to know how to do that.
I am complete new, writting matlab .m files is also new to me. I don't know anymore whom I should ask.
Please help me please..
I really appriciate all the help you can give me.
Thanksyou very much in advance.

OK... I have ogt an idea...but it doesn't work...
I got error massage saying : it can be changed during simulation run time....I guess it is not possible..