how to control a contant/ trigger signal in simulink FROM an m-file?

Hi! I'm using an m file to control a simulation (simulink slx file). The user enters the stop time. When the simulation time reaches its half value, (ie halfway through the simulation,) I need to change a constant from 0 to 1. when it reaches 75%, I need to change the (same) constant source from 1 to 0.

so my question is, how do we control the value of the constant block (or any other block that can produce a const, eg. a step block, or signal generator) with respect to the simulation time from an m file?

Please help me.. I googled a lot but couldn't find a solution thanks

[vainateya goldar]

just to add a detail: I can embed a code in the simulnk also. for example, if stop_time is the stoptime of the model, then, if possible, i can write a code in the simulink model itself to change the const value at stop_time/2 and 3*stop_time/4 instead of using an m file

Answer 1

[vainateya goldar]

oh I myself found the soln :) kinda dumb of me ;)

you simply need the FROM WORKSPACE block. enter a 2-columned matrix in it, 1st column contains time with respect to stop time and 2nd contains const values........

not removing this question in case anybody needs it