40 Keysight E8402A, E8404A C-Size Mainframes User and Service GuideUsing the Enhanced Monitor Using the History QueueUsing the History QueueThe Keysight E840x Enhanced Monitor provides many history feature recordssuch as: minimum and maximum values, histograms, operating times, and eventlogs. As you begin to use the mainframe, the history features won’t be of muchuse -- very little has happened, there is no history to record. But as time passes,the history features can provide valuable insights into the trends of your testsystem. Then, when you encounter a problem in your tests system, you have arecord of events to evaluate:– What type of environment has the module experienced?– What events led up to the failure?– What changes from one test system to another?Over time, familiarity with the problems of one particular test system may lead topredictive knowledge about the system. Then, by watching those predictiveevents using the history feature, you can prevent problems.HISTory QueueOne of the history features is history queue – a list of events that occurred in themainframe. History events are recorded with the operating time that the eventtook place (the operating time is the number of seconds since the mainframewas manufactured). The history queue is available through the display; operatingtime is displayed in hours. Operating Events are shown with the most recentdisplayed first, earliest events displayed last. Figure 5 shows an example historydisplay.To access the history queue, select History from the Mainframe Status display orexecute the command: DISP:WIND HQU. Use the Up/Down arrow keys to pageup and down the list (Up/Down arrows appear in the display only whenadditional data is available) four events at a time.Figure 2-5 Example History Queue DisplayDown arrow indicatesmore data is available.Use Up/Down keys toscroll through display.
