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Chapter 2

Function Reference — GPCTR_Set_Application

NI-DAQ FRM for PC Compatibles

2-226

National Instruments Corporation

Figure 2-18 shows one possible use of a counter for

ND_TWO_SIGNAL_EDGE_SEPARATION_MSR

after the following programming sequence:

GPCTR_Control (deviceNumber, gpctrNum, ND_RESET)

GPCTR_Set_Application (deviceNumber, gpctrNum,

ND_TWO_SIGNAL_EDGE_SEPARATION_MSR)

GPCTR_Control (deviceNumber, gpctrNum, ND_PROGRAM)

In Figure 2-18, the following behavior is present:

•

Gate is the signal present at the counter gate input.

•

Second Gate is the signal present at the counter second gate input.

•

Source is the signal present at the counter source input.

•

Count is the value you would read from the counter if you called the

GPCTR_Watch

function entityID =

ND_COUNT

. The different numbers illustrate the behavior at different

times.

•

Armed is the value you would read from the counter if you called the

GPCTR_Watch

function with entityID =

ND_ARMED

. The different values illustrate behavior at different

times.

Figure 2-18. Start-Stop Measurement

Use the

GPCTR_Watch

function with entityID =

ND_ARMED

to monitor the progress of the

counting process. This measurement completes when entityValue becomes

ND_NO

. When the

counter is no longer armed, you can retrieve the counted value by using

GPCTR_Watch

with

entityID =

ND_COUNT

, as shown in the following example code:

Create U32 variable counter_armed.

Create U32 variable counter_value.

repeat

Source

Count

Armed

Second Gate

Gate

YES