National Instruments NI USB-621x User Manual

Also see for Data Acquisition Device NI USB-621x: User manual

Contents

National Instruments NI USB-621x User Manual Manual pdf 121 page image

Chapter 10 PFI© National Instruments Corporation 10-3 NI USB-621x User ManualMost functions allow you to configure the polarity of PFI inputs andwhether the input is edge or level sensitive.Exporting Timing Output Signals Using PFI TerminalsYou can route any of the following timing signals to any PFI outputterminal.• 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 OutputNote Signals with a * are inverted before being driven to a terminal; that is, these signalsare active low.Using PFI Terminals as Static Digital I/OsEach 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 staticdigital output, called P1.x.Connecting PFI Input SignalsAll PFI input connections are referenced to D GND. Figure 10-3 shows thisreference, and how to connect an external PFI 0 source and an externalPFI 2 source to two PFI terminals.