National Instruments NI PXI-1056 - Manual (Page 13)

Chapter 1 Getting Started
NI PXI-1056 User Manual 1-6 ni.com
The star trigger slot can also be used to provide a PXI_CLK10 signal to the
backplane. For more information regarding PXI_CLK10, refer to the
System Reference Clock section.
Peripheral Slots
There are 17 3U-sized peripheral slots including the star trigger slot. Three
of these slots can only be used for 3U modules. The chassis has a number
of peripheral slots that can also be used in a 6U configuration. They can be
used for a mix of 3U and 6U modules, or they can be used to hold up to
7 6U modules.
Local Bus
The PXI backplane local bus is a daisy-chained bus that connects each
peripheral slot with adjacent peripheral slots (refer to Figure 1-3). For
example, slot 2’s right local bus connects to slot 3’s left local bus, and so on.
The left local bus signal lines on slot 2 are used for star trigger and do not
connect to slot 1. The right local bus signal lines on slots 4, 11, and 18 are
not routed anywhere. Likewise, the left local bus signal lines on shots 5 and
12 are not routed anywhere.
Each local bus is 13 lines wide and can pass analog signals up to 42 V
between cards or provide a high-speed TTL side-band digital
communication path that does not reduce the PXI bus bandwidth.
Initialization software uses the configuration information specific to
adjacent peripheral modules to evaluate local bus compatibility.