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When performing dynamic acquisition with the NI 654X/655X, the source 
generating the signals needs a matched source impedance as close to 50

Ω

 

as 

possible to minimize signal reflections and maintain optimal signal quality. 
Figure 7 shows a diagram of a dynamic acquisition system using the NI 655X 
as an example.

 

Figure 7.  Dynamic Acquisition Functional Diagram

NI digital waveform generator/analyzers have various input 

impedance settings, as shown in the following table.

Refer to the NI Digital Waveform Generator/Analyzer Help for more 
information about signal termination.

Table 3.  Supported Impedance Settings

NI 654X

10 k

Ω

NI 655X

50

Ω

 or 10 k

Ω

NI 656X

*

100

Ω

 for channels configured for 

LVDS operation; 10 k

Ω

 for channels 

configured for single-ended operation

*

 NI 656X cables use 100

Ω 

differential impedance rather than 50

Ω

 single-ended 

impedance.

NI 655

X

NI CB-2162

R

S

R

T

Peripheral
Device

50     Cable