User's Manual Part 2

Plot–Assisted Setups
RVP8 User’s Manual
April 2003
4–4
4.3 General Conventions Within the Plot Commands
The “Pb”, “Ps”, and “Pr” commands all have a similar structure to their TTY user interface.
Each command begins by printing a list of subcommands that are valid in that context. These
subcommands are single keystrokes that are executed immediately by the RVP8 as they are
typed. The “ENTER” key is not required. The available subcommands are different for each
plot command; but, as much as possible, each key has a similar meaning across all commands.
The working and measured parameters for each plot command are printed on the TTY as two
lines of information following the subcommand list. The first line contains settings that only
change when a subcommand is issued; but the second line is live and reflects the current status
of the burst input, the IF input, or the AFC output. The first line is printed just once, but the
second line is continually overprinted on top of itself. This makes it appear as a live status line
whose values always remain up to date. The ”Pb”, ”Ps”, and ”Pr” commands will report ”No
Trigger” on the TTY status line whenever the external trigger is expected but missing.
The TTY screen will scroll upward each time a new subcommand is executed, so that a history
of information lines and command activity can be seen on the screen. You may also use the
Carriage-Return key to scroll the display up at any time. If the initial list of subcommands
disappears off the top, you may type “?” to force a reprint. To exit the plot command entirely
and return to the TTY main menu type “Q” or ESC. These basic “help” and “exit” keystrokes
apply everywhere within the RVP8 setup menus. To save space and minimize clutter on the
TTY screen, they are not shown in the itemized list of subcommands.
Most commands have a lowercase and an uppercase version. If a lowercase command does
something, then its uppercase version does the same thing but even more so (or in reverse). For
example, if the “w” subcommand widens something by a little bit, then “W” would widen it a
lot. This simple convention reduces the number of different subcommand keys that are needed,
and makes the interface easier to memorize.
The oscilloscope display and TTY status lines are continually updated with fresh data several
times per second. Occasionally it is useful to freeze a plot so that it can be studied in more
detail, or compared with earlier versions. To accomplish this, every plotting command supports
a “Single Step” mode that is accessed by typing the “.” (period) key. This key causes the
oscilloscope display and TTY status lines to freeze in their present state, and the message
“Paused...” will be printed. Subsequently, typing another “.” will single step to the next data
update, but the plot and printout will still remain frozen. Typing “Q” or ESC will exit the plot
command entirely (as they normally do). All other keys return the plot command to its normal
live updating, but the key is otherwise discarded (i.e., subcommand keys are not executed while
exiting from single step mode).
All of the plot commands support subcommands whose only purpose is to alter the appearance
of the display, e.g., zoom, stretch, etc. These subcommands make no changes to the actual
working RVP8 calibrations. However, the display settings are stored in nonvolatile RAM just
like all of the other setup parameters. This means that all previous display settings will be
restored whenever you restart each plot command. This is very convenient when alternating
among the various plots.