Chapter 4
Signal Connections
4-4
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National Instruments Corporation
PFI0/TRIG1
DGND
Input
Output
PFI0/Trigger 1—As an input, this is either one of the
Programmable Function Inputs (PFIs) or the source for the
hardware analog trigger. PFI signals are explained in the
Timing Connections section later in this chapter. The
hardware analog trigger is explained in the Analog Trigger
section in
As an output, this is the TRIG1 signal. In posttrigger data
acquisition sequences, a low-to-high transition indicates the
initiation of the acquisition sequence. In pretrigger
applications, a low-to-high transition indicates the initiation
of the pretrigger conversions.
PFI1/TRIG2
DGND
Input
Output
PFI1/Trigger 2—As an input, this is one of the PFIs.
As an output, this is the TRIG2 signal. In pretrigger
applications, a low-to-high transition indicates the initiation
of the posttrigger conversions. TRIG2 is not used in
posttrigger applications.
PFI2/CONVERT*
DGND
Input
Output
PFI2/Convert—As an input, this is one of the PFIs.
As an output, this is the CONVERT* signal. A high-to-low
edge on CONVERT* indicates that an A/D conversion is
occurring.
PFI3/GPCTR1_SOURCE
DGND
Input
Output
PFI3/Counter 1 Source—As an input, this is one of the
PFIs.
As an output, this is the GPCTR1_SOURCE signal. This
signal reflects the actual source connected to the
general-purpose counter 1.
PFI4/GPCTR1_GATE
DGND
Input
Output
PFI4/Counter 1 Gate—As an input, this is one of the PFIs.
As an output, this is the GPCTR1_GATE signal. This signal
reflects the actual gate signal connected to the
general-purpose counter 1.
GPCTR1_OUT
DGND
Output
Counter 1 Output—This output is from the general-purpose
counter 1 output.
PFI5/UPDATE*
DGND
Input
Output
PFI5/Update—As an input, this is one of the PFIs.
As an output, this is the UPDATE* signal. A high-to-low
edge on UPDATE* indicates that the analog output primary
group is being updated.
Table 4-1.
Signal Descriptions for I/O Connector Pins (Continued)
Signal Name
Reference
Direction
Description
PCI_E.book Page 4 Thursday, June 25, 1998 12:55 PM