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Chapter 3
Hardware Overview
Note
The PFI synchronization clock is the same for all routing operations in which
PFI <0..5> is defined as the output, although the divide-down ratio for this clock (full
rate, first divider, second divider) may be chosen on a per route basis.
Brief Overview of PXI Synchronization Features
PCI eXtensions for Instrumentation (PXI) is a rugged PC-based platform that offers a
high-performance, low-cost deployment solution for measurement and automation systems. PXI
combines the Peripheral Component Interconnect (PCI) electrical bus with the rugged, modular
Eurocard mechanical packaging of CompactPCI and adds specialized synchronization buses and
key software features.
Figure 3-8 provides an overview of the PXI synchronization architecture.
Figure 3-8.
PXI Synchronization Architecture
The PXI trigger Bus, PXI star triggers, and PXI_CLK10 are PXI features that enhance
synchronization. The PXI trigger bus is a multi-drop 8-line bus that goes to every slot. The PXI star
trigger bus is a set of up to 13 point-to-point matched-length connections between the system
timing slot and every slot starting with slot 3 and up to slot 15. The propagation delay between the
system timing slot and each destination slot is matched to within 1ns to achieve low-skew
triggering. PXI_CLK10 is a high quality 10 MHz clock that is distributed with low skew to each
PXI slot. This 10 MHz signal can be sourced from the native PXI backplane oscillator or from the
system timing slot Controller Module installed in the system timing slot (such as the NI PXI-665
x
).
The following sections describe in more detail the use of PXI triggers and PXI star triggers with
the NI PXI-665
x
series.
Star Trigger Bus
System
Conr
troller
Star T
rigger
Controller (Slot 2)
Module
Module
Module
132 Mbytes/s, 33 MHz, 32-bit PCI Bus
PXI Trigger Bus (8 lines)
10 MHz
Clock
