Asynchronous routing, Figure 3-5. asynchronous routing operation, Asynchronous routing -16 – National Instruments NI PXIe-6672 User Manual

Page 29

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Chapter 3

Hardware Overview

NI PXIe-6672 User Manual

3-16

ni.com

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 3-5 illustrates an
asynchronous routing operation.

Figure 3-5. Asynchronous Routing Operation

Some delay is always associated with an asynchronous route, and this
delay varies among NI PXIe-6672 modules, depending on variations in
temperature and chassis voltage. Typical delay times in the NI PXIe-6672
for asynchronous routes between various sources and destinations are
given in Appendix A,

Specifications

.

Asynchronous routing works well if the total system delays are not too long
for the application. Propagation delay could be caused by the following
reasons:

Output delay on the source

Propagation delay of the signal across the backplane(s) and cable(s)

Propagation delay of the signal through the NI PXIe-6672

Time for the receiver to recognize the signal

Both the source and the destination of an asynchronous routing operation
on the NI PXIe-6672 can be any of the following lines:

Any front panel PFI pin (PFI <0..5)

Any PXI star trigger line (PXI_STAR <0..16>)

Any PXI trigger line (PXI_TRIG <0..7>)

Trigger Input

Trigger Output

Propagation Delay

t

pd

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