HP 53131A Operating Manual page 115

Chapter 2 Operating Your Universal Counter
Using the LIMITS Menu Keys
6 Press Limit Modes key until LIM TEST: ON is displayed.
Note that once either the upper or lower limits have been set, the limit
testing is automatically enabled as indicated by the LIM TEST: ON
display, and the Limit Modes indicator.
7 Press Limit Modes key.
ON FAIL: GO ON is displayed.
8 Press any one of the arrow keys to toggle to the next state.
ON FAIL: STOP is displayed. The ON FAIL: STOP function tells the
Counter to stop making measurements when the input signals drift more
than ±10% apart.
9 Press Run key to start making measurements with this limits-testing
choice selected.
Now, if a measurement drifts out of the user-entered limits the Limit
annunciator in the display will light. The Counter will stop making
measurements.
Operating Guide 2-39