hi, i want to derive a model of digital control valve. i dont have physical valve with me. still i have to develop such a simulator which can behave the same as the digital control valve. the working concept of digital control valve is little bit different than normal control valve. here is the working of the valve http://www2.emersonprocess.com/siteadmincenter/PM Daniel Documents/788DVControlValve-DS.pdf can any1 help me out how to do it?