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Chapter 3
Hardware Overview
The signal source for each PXI star trigger line configured as an output can be independently
selected from one of the following options:
•
PFI<0..2> (low skew)
•
PXI_TRIG<0..7>
•
Another PXI star trigger line (PXI_STAR<0..12>)
•
Synchronized time event
•
PXI_CLK10
•
Ground
Tip
Invert Ground to get a logic high.
The PXI star trigger outputs may be synchronized to CLK10 except when routing future time
events. Refer to the
section for more information about the
synchronization clock.
Choosing the Type of Routing
The NI PXI-6683 Series 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
Asynchronous routing is the most straightforward method of routing signals. Any asynchronous
route can be defined in terms of two signal locations: a source and a destination. A digital pulse
or train comes in on the source and is propagated to the destination. When the source signal goes
from low to high, this rising edge is transferred to the destination after a propagation delay
through the module. Figure 3-6 illustrates an asynchronous routing operation.
Figure 3-6.
Asynchronous Routing Operation
Some delay is always associated with an asynchronous route, and this delay varies among
NI PXI-6683 Series modules, depending on variations in temperature and chassis voltage.
Typical delay times in the NI PXI-6683 Series for asynchronous routes between various sources
and destinations are given in Appendix A,
.
Trigger Inp
u
t
Trigger O
u
tp
u
t
Prop
a
g
a
tion Del
a
y
t
pd