@ 

It seems to be a great solution for my problem though i am not familiar with modelica. Anyway, it works.

Thank you.

@Thomas Richard 

it is my carelessness, thanks for your anwser.

@Joe Riel 

It is a simplified charge circuit for Li battery, and a commom solution would consist of pre-charge phase, const current phase, const voltage phase and end-charge phase. The circuit really works because the switch ON/OFF resistance isn't zero (maybe?).  Anyway, thanks for your helpful suggestion.  

@Joe Riel  Here is the digital_connection.msim.

@Joe Riel The problem i came across is not vectorized connections that can be solved by connections manager.  I cannot connect every ports in digital blocks like this.

And i tried to use modelica code editor to generate a new component in my local components but they still cannot be connected.

Then i tried to generate a component like "2to1Mux", it sent an error below. Although i can fix it by define the "SI", they still cannot be connected.

Finally, i searched for the modelica standard library and found there was no digital blocks in MSL4.0.0, could you give me some advice?

@Joe Riel 

thanks for your helpful answer.