National Instruments PXIe-6674, Руководство пользователя

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You can independently select the output signal source for the PXI star trigger line from one of
the following sources:
•
PFI<0..5>
• PFI_LVDS<0..2>
• PXI_TRIG<0..7>
• Global software trigger
• Backplane synchronization clock
• PXIe_DSTARB
• Steady logic high or low
Refer to the Using the PXI Triggers section for more information on the backplane
synchronization clock.
Using the PXIe_DSTARB and PXIe_DSTARC Triggers
To improve beyond the performance the PXI Star triggers offer in low skew trigger routing,
PXI Express implements PXIe_DSTARB and PXIe_DSTARC triggers. Each PXI Express
peripheral slot in a PXI Express chassis has independent PXIe_DSTARB and PXIe_DSTARC
connections with the system timing slot module. This allows peripheral modules to send
triggers to the system timing module using PXIe_DSTARC and for the system timing module
to send triggers to peripheral modules using PXIe_DSTARB. Both PXIe_DSTARB and
PXIe_DSTARC are one directional. The PXI Express Specification requires PXI Express
chassis to limit the skew between any two PXIe_DSTAR routes to 150 ps.
The PXIe-6674 receives PXIe_DSTARB and can route it as a trigger source. The PXIe-6674
can independently select from the following sources to be routed to PXIe_DSTARC:
•
PFI<0..5>
• PFI_LVDS<0..2>
• PXI_TRIG<0..7>
• PXI Star Trigger
• PXIe_DSTARB
• Global Software Trigger
• Steady logic high or low
• Backplane synchronization clock.
Refer to the Using the PXI Triggers section for more information on the backplane
synchronization clock.
Choosing the Type of Routing
The PXIe-6674 routes signals in one of two ways: asynchronously or synchronously. The
following sections describe the two routing types and the considerations for choosing each
type.
Asynchronous routing is the most straightforward method of routing signals. Any
asynchronous route can be defined in terms of two signals: a
source and a destination . A
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