HP 54620A User's And Service Manual page 211

Messages
Delay at limit
You have exceeded either the positive or negative time limit for the sweep
delay. The limits depend on the current Time/Div setting, sampling rate, and
whether the Horizontal Mode is Main or Delayed. See Chapter 4, "Ensuring
Accurate Measurements," for more information on interaction between time
functions in the analyzer.
Delay at limit - use delayed sweep to view large negative time
This message appears when you set the analyzer to a much faster sweep
speed after a single acquisition, where the delay setting is large, but the
delayed sweep window is off (main only). To see the desired part of the
waveform, change the sweep speed to a slower setting, turn the delayed
sweep on, or do both.
Delay =
When the Horizontal Mode is Delayed, this message appears while you are
adjusting the Delay knob, to inform you of the current delay time setting.
Duration time at limit
This message appears when, in the Advanced Trigger menu, you try to adjust
the duration setting for a pattern to a value less than the minimum or greater
than the maximum. The minimum and maximum values are determined by
the Time/Div and sampling interval, so you may be able to work around the
problem by changing the Time/Div setting. See Chapter 4, "Ensuring
Accurate Measurements," for more information on the interaction between
various analyzer time base functions.
Front panel locked
This message appears when an instrument controller, such as a PC or
workstation, has locked the analyzer's front panel using the SYSTem:LOCK
command.
Illegal Instruction
A processing fault occurred during operation. Cycle power to the analyzer, or
perform a hard reset by cycling power with the two rightmost softkeys
depressed. If this does not correct the problem, contact your HP Sales Office
for assistance.
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