National Instruments Isolated Analog Input Device NI PXI-4224 - Manual (Page 59)

Appendix B Timing Signal Information
© National Instruments Corporation B-3 NI PXI-4224 User Manual
AI START TRIG Signal
The AI START TRIG signal can be input or output through PFI 0,
PXI_Trig<0..5>, or PXI_Star.
As an input, AI START TRIG is configured in the edge-detection mode.
You can select PFI 0 as the source for AI START TRIG and configure the
polarity selection for either rising or falling edge. The selected edge
of AI START TRIG starts the sequence for both posttriggered and
pretriggered acquisitions. Refer to Figures B-1 and B-2 for the relationship
of AI START TRIG to the sequence.
As an output, AI START TRIG reflects the action that initiates a sequence,
even if the acquisition is 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
high-impedance at startup.
Figures B-3 and B-4 show the input and output timing requirements
for AI START TRIG.
Figure B-3. AI START TRIG Input Signal Timing
Figure B-4. AI START TRIG Output Signal Timing
Rising-Edge
Polarity
Falling-Edge
Polarity
t
w
= 10 ns minimum
t
w
t
w
= 50 to 100 ns
t
w