Agilent Technologies 4000 X Servisní příručka stáhnout pdf (Strana 140)

140 4000 X-Series Oscilloscopes Advanced Training Guide

4 Serial Bus Decoding & Triggering, Search & Navigation, and Segmented Acquisition Labs

7 Press [Serial] on the front panel of the scope.

8 In the Mode menu, select ARINC 429.

9 In the Signals menu, set High Threshold to +1.0 V and Low Threshold to

-1.0 V. These determine how high or low a signal needs to go to qualify

for logic levels. In a true ARINC 429 signal, the signal voltages are set

to +10 V, but for this example signal, they are only +2.5 V. ARINC 429

protocol suggests a range of 3- 6 V. Set your thresholds on true signals

accordingly.

You should now see ARINC 429 serial information being actively decoded

on the bottom of the waveform. Agilent's hardware based decoding allows

for extremely fast update and decode rates, allowing you to read the

information as it passes along the screen. Next, let's set up a trigger point,

as we are still triggering on random rising edges.

10 Press [Trigger] on the front panel, and in the Trigger Type menu, select

Serial 1: ARINC 429.

11 There are many different options in the Trigger menu for you to choose

from; for this example, select Word Start. This will trigger on all legal

words. You should now have a stable trigger, as in Figure 95.

Figure 94 Random edge triggering on ARINC-429 traffic.

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Agilent Technologies 4000 X Servisní příručka Strana 140