National Instruments NI USB-621x Using PFI Terminals as Static Digital I/Os, Connecting PFI Input Signals, Exporting Timing Output Signals Using PFI Terminals

Chapter 10 PFI

Most functions allow you to configure the polarity of PFI inputs and whether the input is edge or level sensitive.

Exporting Timing Output Signals Using PFI Terminals

You can route any of the following timing signals to any PFI output terminal.

•AI Convert Clock*

•AI Hold Complete Event

•AI Reference Trigger

•AI Sample Clock

•AI Start Trigger

•AO Sample Clock*

•AO Start Trigger

•Counter n Source

•Counter n Gate

•Counter n Internal Output

•Frequency Output

Note Signals with a * are inverted before being driven to a terminal; that is, these signals are active low.

Using PFI Terminals as Static Digital I/Os

Each input PFI line can be individually configured as a static digital input, called P0.x. Each output PFI line can be individually configured as a static digital output, called P1.x.

Connecting PFI Input Signals

All PFI input connections are referenced to D GND. Figure 10-3shows this reference, and how to connect an external PFI 0 source and an external PFI 2 source to two PFI terminals.

© National Instruments Corporation 10-3 NI USB-621x User Manual