I am using the Linear Analyzer to analyze a simple PID + valve system and am facing the following issue. The plant is a 1st order with time-delay valve.
The fig. shows the points where the Open-loop input and output were placed and the step-response plotted. The step response looks normal on the scope, but looks to be linearly increasing and unbounded, in the OPEN LOOP step-response obtained in the Linear Analyzer.
The scope does show the same response if I open-loop the simulink model. So is this is normal?