HP 81101A Reference Manual page 63

You cannot set the pulse period if you have selected the CLK-IN
connector as the frequency source (:TRIG:SOUR EXT).
Example
To set the pulse period using the internal oscillator:
:TRIG:SOUR INT
:PULS:PER 25NS
Command
:PULS:PER:AUTO
Long
[:SOURce]:PULSe:PERiod:AUTO
Form
Event
Parameter
ONCE
*RST value
Not applicable
Description
Use this command to measure the period at the CLK-IN connector. If the
CLK-IN connector is the selected pulse period source, you can then read
the measured value with :PULS:PER?
Example
To measure the period at the CLK-IN connector:
:TRIG:SOUR EXT
:PULS:PER:AUTO ONCE
:PULS:PER?
Command
:PULS:TDEL[1]
Long
[:SOURce]:PULSe:TDELay[1]
Form
Set & Query
Parameter
Numeric
Parameter Suffix S with engineering prefixes.
*RST value
100 ns
Specified Limits 10 ns to 999.5 s (max. period –10 ns)
Description
Use this command to program the delay of the trailing edge of the pulse
relative to the start of the pulse period. This is an alternative method of
programming the pulse width.
Programming Reference
SCPI Instrument Command List
Select internal osc. as pulse trigger
Set pulse frequency to 25 ns
Select ext. CLK-IN as pulse trigger
Measure period at CLK-IN
Query pulse period
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