Chapter 4 Signal Connections
VXI-MIO Series User Manual
4-34
National Instruments Corporation
AIGATE does not gate off conversions until the beginning of the next
scan and, conversely, if conversions are being gated off, AIGATE does
not gate them back on until the beginning of the next scan.
SISOURCE Signal
Any PFI pin can externally input the SISOURCE signal, which is not
available as an output on the I/O connector. The onboard scan interval
counter uses the SISOURCE signal as a clock to time the generation of
the STARTSCAN signal. You must configure the PFI pin you select as
the source for the SISOURCE signal in the level-detection mode. You
can configure the polarity selection for the PFI pin for either active high
or active low.
The maximum allowed frequency is 20 MHz, with a minimum pulse
width of 23 ns high or low. There is no minimum frequency limitation.
Either the 20 MHz or 100 kHz internal timebase generates the
SISOURCE signal unless you select some external source. Figure 4-23
shows the timing requirements for the SISOURCE signal.
Figure 4-23.
SISOURCE Signal Timing
Waveform Generation Timing Connections
The analog group defined for your VXI-MIO Series module is
controlled by WFTRIG, UPDATE*, and UISOURCE.
WFTRIG Signal
Any PFI pin can externally input the WFTRIG signal, which is
available as an output on the PFI6/WFTRIG pin.
t
p
t
w
t
w
t
p
t
w
= 50 ns minimum
= 23 ns minimum
