Ok so i have a transfer function (of a motor) and i want to control it with a PI controller. i put the TF in one block and put in values (that i took from a tutorial for a motor). and then I put the PI in a block before it and feed the output of the plant and add it to the input to go into the input of the controller. but I'm not getting what i'm expecting. in labs i'm used to having the setup ready and when it comes to adding the PI control i have just tried different gains and looked at the step response. How do i do this in simulink? do i just simply put a step response block as the input (that the feedback is added to what is being fed back). do i just simply put a step response(or impulse or whatever) block on the input and a scope on the output. the graphs i've been getting makes no sense so i must be doing a silly mistake somewhere. after i've done this in simulink can i save the file and then use matlab to find the root locus of the controlled. as in use the root locus command on my saved file and it will draw it? also can i put in the letters into the transfer function in simulink and outside in the matlab screen set these values.