National Instruments 320682C - page 388

Chapter 10 Easy I/O for DAQ Library
© National Instruments Corporation 10-31 LabWindows/CVI Standard Libraries
Parameters
Input device short
integer Assigned by configuration utility.
counter string The counter to be used for the counting
operation.
counterSize unsigned
short
integer
Determines the size of the counter used to
perform the operation: ONE_COUNTER or
TWO_COUNTERS.
gateWidthSampleTimeinSec double The desired length of the pulse used to gate
the signal. The lower the signal frequency,
the longer the Gate Width must be.
maxDelayBeforeGateSec double The maximum expected delay between the
time the function is called and the start of
the gating pulse. If the gate signal does not
start in this time, a timeout occurs.
counterMinus1GateMode unsigned
short
integer
The gate mode for counter-1.
Output actualGateWidthSec double The length in seconds of the gating pulse
that is used.
overflow short
integer 1 = counter rolled past terminal count; 0 = counter did not roll past terminal count. If
overflow is 1, the value of frequency is
inaccurate.
valid short
integer Set to 1 if the measurement completes without a counter overflow. A timeout and
a valid measurement may occur at the same
time. A timeout does not produce an error.
timeout short
integer Set to 1 if the time limit expires during the function call. A timeout and a valid
measurement may occur at the same time.
A timeout does not produce an error.
frequency double The frequency of the signal. It is computed
as the (number of rising edges) /
(actualGateWidthSec).