National Instruments Welding System 321645c-01 ユーザーズマニュアル
Chapter 2
Function Reference — GPCTR_Set_Application
NI-DAQ FRM for PC Compatibles
2-232
©
National Instruments Corporation
Figure 2-21. Retriggerable Pulse 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_RETRIG_PULSE_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
if you are using
ND_INTERNAL_20_MHZ
timebase.
•
ND_GATE
to any legal value listed in the
GPCTR_Change_Parameter
function
description.
•
ND_GATE_POLARITY
to
ND_NEGATIVE
. A high-to-low transition of the gate signal
initiates the pulse generation timing.
You can use the
GPCTR_Change_Parameter
function after calling
GPCTR_Set_Application
and before calling
GPCTR_Control
with
action =
ND_PROGRAM
or
ND_PREPARE
.
To provide your timebase, you can connect your timebase source to one of the PFI pins on the
I/O connector and change
I/O connector and change
ND_SOURCE
and
ND_SOURCE_POLARITY
to the appropriate values.
You also can configure the other general-purpose counter for
ND_RETRIG_PULSE_GNR
, and
set
ND_SOURCE
of this counter to
ND_OTHER_GPCTR_TC
to generate pulses with delays and
intervals longer than 160 s.
application =
ND_PULSE_TRAIN_GNR
In this application, the counter is used for generation of a pulse train. By default, you get this
by using the 20 MHz internal timebase (
by using the 20 MHz internal timebase (
ND_INTERNAL_20_MHZ
), so the resolution of timing
is 50 ns. By default, the counter repeatedly counts down from
ND_COUNT_1
= 5 million to 0
for the delay time and then down from
ND_COUNT_2
= 10 million to 0 for the pulse generation
time to generate a train of 0.5 s pulses separated by 0.25 s of delay. Pulse train generation
starts as soon as you arm the counter. You must reset the counter to stop the pulse train.
starts as soon as you arm the counter. You must reset the counter to stop the pulse train.
Source
Gate
Output
Count_1=3
Count_2=4
Count_1=3
Count_2=4
Count_1=3
Count_2=4