National Instruments 321645c-01 Welding System User Manual


 
Chapter 2 Function Reference GPCTR_Set_Application
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National Instruments Corporation 2-219 NI-DAQ FRM for PC Compatibles
Figure 2-15 shows one possible scenario of a counter used for ND_SINGLE_PERIOD_MSR
after the following programming sequence:
GPCTR_Control(deviceNumber, gpctrNum, ND_RESET)
GPCTR_Set_Application(deviceNumber, gpctrNum,
ND_SINGLE_PERIOD_MSR)GPCTR_Set_Application
GPCTR_Control(deviceNumber, gpctrNum, ND_PROGRAM)
In Figure 2-15, the following behavior is present:
Gate is the signal present at the counter 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 with entityID =
ND_COUNT. The different numbers illustrate 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 2-15.
Single Period 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. You can do this as follows:
Create u32 variable counter_armed.
Create u32 variable counted_value.
repeat
{
GPCTR_Watch(deviceNumber, gpctrNumber, ND_ARMED, counter_armed)
}
01
YES
YES
23
4
4
44
Gate
Source
Count
Armed
Measured
Interval
NO
NO
NO