National Instruments E Series - Manual (Page 63)

Chapter 4 Signal Connections
 National Instruments Corporation 4-27 DAQCard E Series User Manual
EXTSTROBE* Signal
EXTSTROBE* is an output-only signal that generates either a single
pulse or a sequence of eight pulses in the hardware-strobe mode. An
external device can use this signal to latch signals or to trigger events.
In the single-pulse mode, software controls the level of the
EXTSTROBE* signal. A 10 and 1.2
µ
s clocks are available for
generating a sequence of eight pulses in the hardware-strobe mode.
Figure 4-13 shows the timing for the hardware-strobe mode
EXTSTROBE* signal.
TRIG1 Signal
Any PFI pin can externally input the TRIG1 signal, which is available
as an output on the PFI0/TRIG1 pin.
Refer to Figures 4-10 and 4-11 for the relationship of TRIG1 to the
data acquisition sequence.
As an input, the TRIG1 signal is configured in the edge-detection
mode. You can select any PFI pin as the source for TRIG1 and
configure the polarity selection for either rising or falling edge. The
selected edge of the TRIG1 signal starts the data acquisition sequence
for both posttriggered and pretriggered acquisitions. The DAQCards
support analog triggering on the PFI0/TRIG1 pin. See Chapter 3 for
more information on analog triggering.
As an output, the TRIG1 signal reflects the action that initiates a data
acquisition sequence. This is true even if the acquisition is being
externally triggered by another PFI. The output is an active high pulse
with a pulse width of 50 to 100 ns. This output is set to tri-state at
startup.
Figure 4-13. EXTSTROBE* Signal Timing
t
w
t
w
V
OH
V
OL
t
w
= 600 ns or 5 µ s