Chapter 3
Connecting the Signals
©
National Instruments Corporation
3-27
DAQCard-1200 User Manual
Figure 3-17 illustrates a waveform generation timing sequence using the
EXTUPDATE* signal and the delayed update mode. The DACs are
updated by a high level on the DAC OUTPUT UPDATE signal, which in
this case is triggered by a low level on the EXTUPDATE* line. The
counter-interrupt signal interrupts the computer. This interrupt is generated
on the rising edge of EXTUPDATE*. The DACWRT signal writes a new
value to the DAC.
Figure 3-17.
EXTUPDATE* Signal Timing for Updating DAC Output
Note
You should configure both DACs in either immediate update mode or in later update
mode, but not in a combination of the two modes. Although you can configure the DACs
in a combination of modes, doing so can result in glitches on the immediate update DAC
if the update rate on the waveform DAC is high. Refer to the
section in
, for details on this behavior.
The following rating applies to the EXTCONV*, EXTTRIG, OUTB1, and
EXTUPDATE* signals.
•
Absolute maximum voltage input rating
–
0.5 to 5.5 V with respect
to DGND
Refer to the NI-DAQ manual or to Chapter 4,
, for
more information concerning the various modes of data acquisition and
analog output.
General-Purpose Timing Connections
General-purpose timing signals include the GATE, CLK, and OUT signals
for the three 82C53(B) counters. The 82C53 counter/timers can be used for
many general-purpose applications such as pulse and square wave
generation; event counting; and pulse-width, time-lapse, and frequency
DACWRT
Counter Interrupt
DAC OUTPUT
UPDATE
EXTUPDATE*
t
w
50 ns min
Summary of Contents for DAQPad-1200
Page 1: ...DAQPad 1200...
