Chapter 3 Hardware Overview
NI PCI-6110/6111 User Manual 3-10 ni.com
Programmable Function Inputs
The 10PFIs are connected to the signal routing multiplexer for each timing
signal, and software can select a PFI as the external source for a given
timing signal. Any PFI can be used as an input by any timing signal, and
multiple timing signals can simultaneously use the same PFI. This flexible
routing scheme reduces the need to change physical connections to the
I/Oconnector for different applications. You can also individually enable
each PFI pin to output a specific internal timing signal. For example, if you
need the UPDATE* signal as an output on the I/O connector, software can
turn on the output driver for the PFI5/UPDATE* pin.
Device and RTSI Clocks
Many functions performed by the NI PCI-6110/6111 require afrequency
timebase to generate the necessary timing signals for controlling A/D
conversions, DAC updates, or general-purpose signals at the I/O connector.
The NI PCI-6110/6111 can use either its internal 20 MHz timebase or a
timebase received over the RTSI bus. In addition, if you configure the
device to use the internal timebase, you can program the device to drive its
internal timebase over the RTSI bus to another device that is programmed
to receive this timebase signal. This clock source, whether local or from the
RTSI bus, is used directly by the device as the primary frequency source.
The default configuration at startup is to use the internal timebase without
driving the RTSI bus timebase signal. This timebase is software-selectable.