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L4450A 64-Bit Digital I/O with Memory and Counter 8
L4400 User’s Guide 217
MEAS:COUN:TOT? RRES, (@1301)
Totalizer counts begin as soon as the channel is configured for the totalize
measurement. You can stop a count by sending
SENSe:COUNter:ABORt
command and restart the count using the SENSe:COUNter:INITiate
command.
The slope of the edges being counted can be configured using the
SENSe:COUNter:SLOPe command. By default, when started, the totalizer
counts rising edges.
Additionally, you can control when the edges are counted by setting the gate
source to external and providing a gate signal on the gate input.
In external gate mode the counter totalizes when the gate is asserted.
The gate time setting controls how long the counter totalizes. Once the
external gate has been de- asserted a new measurement must be armed via the
SENSe:COUNter:INITiate command. The figure below shows an externally
gated totalizer measurement. The number of totalized counts is ‘5’ in this
particular example.
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 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.
Init
Ext Gate
Input