![NI PXI-4220 Скачать руководство пользователя страница 101](http://html1.mh-extra.com/html/ni/pxi-4220/pxi-4220_user-manual_1685516101.webp)
Appendix B
Timing Signal Information
©
National Instruments Corporation
B-5
NI PXI-4220 User Manual
Figure B-6.
AI REF TRIG Output Signal Timing
AI SAMP CLK Signal
The AI SAMP CLK signal can be externally input from PFI0,
PXI_Trig<0..5>, or PXI_Star. It can be output on any PXI trigger bus line.
Refer to Figures B-1 and B-2 for the relationship of AI SAMP CLK to the
sequence.
As an input, AI SAMP CLK is configured in edge-detection mode.
You can configure the polarity selection for either rising or falling edge.
The selected edge of AI SAMP CLK initiates a scan. The SI2 counter
starts if you select an internally triggered AI CONV CLK.
As an output, AI SAMP CLK reflects the actual start pulse that initiates
a scan, even if the starts are externally triggered by another PFI,
PXI_Trig<0..5>, or PXI_Star. You have two output options. The first
option is an active high pulse with a pulse width of 50 to 100 ns, which
indicates the start of the scan. The second option is an active high pulse that
terminates at the start of the last conversion in the scan, which indicates a
scan in progress. AI SAMP CLK is deasserted, t
off
, after the last conversion
in the scan is initiated. This output is set to high-impedance at startup.
Figures B-7 and B-8 show the input and output timing requirements
for AI SAMP CLK.
t
w
= 50 to 100 ns
t
w
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com