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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 

 section.

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.

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.