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Chapter 1 Getting Started
System Reference Clock
The PXIe-1095 chassis supplies PXI_CLK10, PXIe_CLK100, and PXIe_SYNC100
independently driven to each peripheral slot.
An independent buffer (having a source impedance matched to the backplane and a skew of less
than 250 ps between slots) drives PXI_CLK10 to each slot. You can use this common reference
clock signal to synchronize multiple modules in a measurement or control system.
An independent buffer drives PXIe_CLK100 to each peripheral slot. These clocks are matched
in skew to less than 100 ps. The differential pair must be terminated on the peripheral with
LVPECL termination for the buffer to drive PXIe_CLK100 so that when there is no peripheral
or a peripheral that does not connect to PXIe_CLK100, there is no clock being driven on the pair
to that slot.
An independent buffer drives PXIe_SYNC100 to each peripheral slot. The differential pair must
be terminated on the peripheral with LVPECL termination for the buffer to drive
PXIe_SYNC100 so that when there is no peripheral or a peripheral that does not connect to
PXIe_SYNC100, there is no SYNC100 signal being driven on the pair to that slot.
PXI_CLK10, PXIe_CLK100 and PXIe_SYNC100 have the default timing relationship
described in Figure 1-6.
Figure 1-6. System Reference Clock Default Behavior
To synchronize the system to an external clock, you can drive PXI_CLK10 from an external
source through the PXI_CLK10_IN pin on the System Timing Slot, or from an external SMA
connector on the rear of the chassis (Timing and Synchronization upgrade). Refer to Table A-8,
XP4 Connector Pinout for the System Timing Slot, for the pinout. When an external clock is
detected, the backplane automatically phase-locks the PXI_CLK10, PXIe_CLK100, and
PXIe_SYNC100 signals to this external clock and distributes these signals to the slots. Refer to
the PXIe-1095 Specifications for the specification information for an external clock provided on
the PXI_CLK10_IN pin of the system timing slot or rear panel SMA.
PXIe_CLK100
PXI_CLK10
PXIe_SYNC100
0123 45678 90123 45678 90123 45678 9
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