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Chapter 4

Signal Connections

 National Instruments Corporation

4-19

Figure 4-11 shows the timing for the hardware-strobe mode 
EXTSTROBE* signal.

Figure 4-11.  EXTSTROBE* Signal Timing

Any PFI pin can externally input the TRIG1 signal, which is available 
as an output on the PFI0/TRIG1 pin. 

Refer to Figures 4-8 and 4-9 for the relationship of TRIG1 to the DAQ 
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 611X E supports 
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 DAQ 
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 25 to 50 ns. This output is set to tri-state at startup.

t

w

t

w

V OH

V OL

t

w

= 600 ns or 5 

µ

s

PCI_E.book  Page 19  Thursday, June 25, 1998  12:55 PM