National Instruments Welding System 321645c-01 사용자 설명서

Chapter 2

Function Reference — GPCTR_Set_Application

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NI-DAQ FRM for PC Compatibles

With the default 20 MHz timebase, combined with the counter width (24 bits), you can 
generate trains consisting of pulses with delay and length between 100 ns and 0.8 s. For the 
6602 devices, you can generate pulses with a delay and length between 100 ns and 214 s long.

Assume that you want to generate a pulse train with the low period 150 ns long and the high 
period 200 ns long. You need to set 

ND_COUNT_1

 to 150 ns/50 ns = 3 and 

ND_COUNT_2

 to 

200 ns/50 ns = 4. This corresponds to a 20 MHz: (3 + 4) = 2.86 MHz signal 
with (3/7)/(4/7) = 43/57 duty cycle. Figure 2-22 shows the scenario of a counter used for 

ND_PULSE_TRAIN_GNR

 after the following programming sequence:

GPCTR_Control(deviceNumber, gpctrNum, ND_RESET) 

GPCTR_Set_Application(deviceNumber, gpctrNum, ND_PULSE_TRAIN_GNR)

GPCTR_Change_Parameter(deviceNumber, gpctrNum, ND_COUNT_1, 3) 

GPCTR_Change_Parameter(deviceNumber, gpctrNum, ND_COUNT_2, 4) 

Select_Signal(deviceNumber, gpctrNumOut, gpctrNumOut, ND_LOW_TO_HIGH)

GPCTR_Control(deviceNumber, gpctrNum, ND_PROGRAM) 

In Figure 2-22, the following behavior is present:

•

Source is the signal present at the counter source input.

•

Output is the signal present at the counter output.

Figure 2-22.  Pulse Train Generation

Use the 

GPCTR_Control

 function with action = 

ND_RESET

 to stop the pulse generation.

Typically, you will find modifying the following parameters through the 

GPCTR_Change_Parameter

 function useful when the counter application is 

ND_PULSE_TRAIN_GNR

. You can change the following:

•

ND_COUNT_1

 and 

ND_COUNT_2

 to any value between 2 and 2

24

 – 1. The defaults are 

given for illustrative purposes only. 

•

ND_SOURCE

 to 

ND_INTERNAL_100_KHZ

. With this timebase, you can generate pulses 

with delay and length between 20 µs and 160 s. The timing resolution will be lower than 
if you are using the 

ND_INTERNAL_20_MHZ

 timebase. 

Source

Count_1 = 3

Count_2 = 4

Count_1 = 3

Count_2 = 4

Output