286 34980A User’s Guide
10 64-Bit Digital I/O Module with Memory and Counter
Initiated Measurement Mode
Measurements such as frequency, period, duty cycle, and pulse width 
require an initiate command and a gate. The 
SENSe:COUNter:INITiate 
command is used to initiate (arm) the measurement. The measurement 
is gated by either an internal (default) or the external gate source. 
For measurements the external gate acts like an external trigger which 
triggers the internal gate timer. 
The gate source is set using the 
SENSe:COUNter:SOURce command. 
The default gate source is INTernal. The gate is the aperture over which 
the signal data is gathered. When the gate is internal, the measurement 
begins as soon as the INITiate command is received.
Since the measurements are all derived from the same basic measurement, 
you can retrieve the measured frequency, period, duty- cycle, and pulse 
width from the same initiated and gated measurement. For example, the 
following commands set the counter to measure the input signal for 1 ms 
using the internal gate. The frequency, period, duty cycle, and pulse width 
are returned as floating point numbers.
CONF:COUN:FREQ 1e-3, (@1301)
SENS:COUN:INIT (@1301)
SENS:COUN:FREQ? (@1301)
SENS:COUN:PER? (@1301)
SENS:COUN:PWID? (@1301)
SENS:COUN:DCYC? (@1301)
The  CONFigure:COUNter:FREQuency command parameter sets the internal 
gate time (to 1e-3 or 1 ms in the above example). You can also set the 
gate time using the SENSe:COUNter:GATE:TIME command.