TDS 620A, 640A, & 644A User Manual
Limit T esting
Limit testing provides a way to automatically compare each incoming or math
waveform against a template waveform. You set an envelope of limits around
a waveform and let the digitizing oscilloscope find waveforms that fall outside
those limits (see Figure 3-40). When it finds such a waveform, the digitizing
oscilloscope can generate a hardcopy, ring a bell, stop and wait for your input,
or any combination of these actions.
Figure 3-40: Comparing a Waveform to a Limit Template
When you use the limit testing feature, the first task is to create the limit test
template from a waveform. Next, specify the channel to compare to the
template. Then you specify the action to take if incoming waveform data
exceeds the set limits. Finally, turn limit testing on so that the parameters you
have specified will take effect.
To access limit testing:
Press SHIFT ACQUIRE MENU to bring up the Acquire menu.

Create Limit Test Template

To use an incoming or stored waveform to create the limit test template, first
select a source.
1. Press Create Limit Test Template (main) Template Source (side)
Ch1, Ch2, Math1, Math2, Math3, Ref1, Ref2, Ref3, or Ref4 (side). (See
Figure 3-41).
Operation