title: Scope displays unexpected puls generator output
body: <p>I am having troubles understanding the output of my scope in this simple simulink model:</p>
  
  <p><img src="https://i.stack.imgur.com/BwQEQ.png" alt="puls_gen and scope"></p>
  
  <p>I am using a fixed step solver (tried with ode3 and ode8).
  <code>Pulse type</code> of the puls generator is set to <code>Sample based</code> and I varied the <code>Period</code> and <code>Pulse Width</code>.</p>
  
  <p>First I set the simulation time to 10 and set the puls generator to <code>Period = 10</code> and <code>Puls width = 5</code>. The output of the scope is as expected:</p>
  
  <p><img src="https://i.stack.imgur.com/4OohS.png" alt="period=10"></p>
  
  <p>But when I tried with simulation time 10,000 and the puls generator with <code>Period = 1,000</code> and <code>Puls width = 500</code> it seems my scope is wrong:</p>
  
  <p><img src="https://i.stack.imgur.com/9uoKu.png" alt="enter image description here"></p>
  
  <p>Why is the first falling edge at 5,500? I used the Autoscale button every time.</p>
  
  <p>Using sim time 100,000 and <code>Period = 10,000</code> and <code>Puls width = 5,000</code> I don't even get a single falling edge:</p>
  
  <p><img src="https://i.stack.imgur.com/IfBBT.png" alt="enter image description here"></p>
  
  <p>Even with longer simulation time there seems to be a single rising edge at the end of the scope window.</p>
  
  <p>What am I doing wrong? Is the scope not suitable for such long simulation times using fixed step solver? Or is it not "safe" to use the Autoscale button?</p>