National Instruments Welding System 321645c-01 Manual De Usuario
Chapter 2
Function Reference — GPCTR_Set_Application
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National Instruments Corporation
2-229
NI-DAQ FRM for PC Compatibles
between 20 ns and 11.37 hours for 6602 and 455X devices. The timing resolution will be
lower than if you are using the
lower than if you are using the
ND_INTERNAL_20_MHZ
timebase.
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_PULSE_TRAIN_GNR
and set
ND_SOURCE
of this counter to
ND_OTHER_GPCTR_TC
to generate pulses with delays and
intervals longer than 160 s for E Series and 445X devices and 11.37 hours for 6602 and 455X
devices.
devices.
application =
ND_SINGLE_TRIG_PULSE_GNR
In this application, the counter is used for the generation of a single delayed pulse after a
transition on the gate input. By default, this is achieved by using the 20 MHz internal timebase
(
transition on the gate input. By default, this is achieved by using the 20 MHz internal timebase
(
ND_INTERNAL_20_MHZ
), so the resolution of timing is 50 ns. By default, the counter 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 0.5 s pulse after
0.25 s of delay. The default gate signal is shown in Table 2-25, and the transition that initiates
the pulse generation is low-to-high. Only the first transition of the gate signal after you arm
the counter initiates pulse generation; all subsequent transitions are ignored.
the pulse generation is low-to-high. Only the first transition of the gate signal after you arm
the counter initiates pulse generation; all subsequent transitions are ignored.
The default 20 MHz timebase, combined with the counter width (24 bits), lets you generate
pulses with a delay and length between 100 ns and 0.8 s (each), for E Series and 445X devices
only. For 6602 and 455X devices with counter width 32 bits, you can generate pulses with a
delay and length between 100 ns and 214 s long.
pulses with a delay and length between 100 ns and 0.8 s (each), for E Series and 445X devices
only. For 6602 and 455X devices with counter width 32 bits, you can generate pulses with a
delay and length between 100 ns and 214 s long.
For example, assume that you want to generate a pulse 200 ns long after 150 ns of delay from
the transition of the gate signal. You need to set
the transition of the gate signal. You need to set
ND_COUNT_1
to 150 ns/50 ns = 3 and
ND_COUNT_2
to 200 ns/50 ns = 4. Figure 2-20 shows the scenario of a counter used for
ND_SINGLE_TRIG_PULSE_GNR
after the following programming sequence:
GPCTR_Control(deviceNumber, gpctrNum, ND_RESET)
GPCTR_Set_Application(deviceNumber, gpctrNum,
ND_SINGLE_TRIG_PULSE_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)