Chapter 1
Getting Started
©
National Instruments Corporation
1-5
For example, a given peripheral slot’s right local bus connects to the
adjacent slot’s left local bus, and so on. Each local bus is 13 lines wide and
can pass analog signals between cards or provide a high-speed side-band
communication path that does not affect the PCI bandwidth.
Local bus signals may range from high-speed TTL signals to analog signals
as high as 42 V. Initialization software keys adjacent boards to prohibit
the use of incompatible boards. This software uses the configuration
information specific to each peripheral board to evaluate compatibility.
This method is a flexible way to define local bus functionality that is not
limited by hardware keying.
Figure 1-3.
PXI Local Bus and Star Trigger Routing
Trigger Bus
The eight PXI trigger lines are bused to each slot. You can use the trigger
lines in a variety of ways. For example, you can use triggers to synchronize
the operation of several different PXI peripheral modules. In other
applications, one module can control carefully timed sequences of
operations performed on other modules in the system. Modules can
pass triggers to one another, allowing precisely timed responses to
asynchronous external events the system is monitoring or controlling.
System Controller Slot 1
Star Trigger/Peripheral Slot 2
Peripheral Slot 3
Peripheral Slot 4
Peripheral Slot 7
Peripheral Slot 8
Local
Bus
Local
Bus
Star Triggers
PCI Arbitration and Cloc Signals
Local
Bus
