80 Mhz Timebase; 100 Khz Timebase; External Reference Clock - National Instruments NI 6221 User Manual

Chapter 9 Digital Routing and Clock Generation

80 MHz Timebase

20 MHz Timebase

100 kHz Timebase

External Reference Clock

M Series User Manual
The 80 MHz Timebase can be used as the Source input to the 32-bit
general-purpose counter/timers.
The 80 MHz Timebase is generated from the following sources.
• Onboard oscillator
• External signal (by using the external reference clock)
The 20 MHz Timebase normally generates many of the AI and AO timing
signals. The 20 MHz Timebase also can be used as the Source input to the
32-bit general-purpose counter/timers.
The 20 MHz Timebase is generated by dividing down the 80 MHz
Timebase.
The 100 kHz Timebase can be used to generate many of the AI and AO
timing signals. The 100 kHz Timebase also can be used as the Source input
to the 32-bit general-purpose counter/timers.
The 100 kHz Timebase is generated by dividing down the 20 MHz
Timebase by 200.
The external reference clock can be used as a source for the internal
timebases (80 MHz Timebase, 20 MHz Timebase, and 100 kHz Timebase)
on an M Series device. By using the external reference clock, you can
synchronize the internal timebases to an external clock.
The following signals can be routed to drive the external reference clock.
• RTSI <0..7>
• PXI_CLK10
• PXI_STAR
The external reference clock is an input to a Phase-Lock Loop (PLL). The
PLL generates the internal timebases.
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