Agilent Technologies 3000 X-Series Manuel de service télécharger pdf (Page 86)

86 3000 X-Series Oscilloscopes Advanced Training Guide

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

You should now see on your scope’s display what appears to be an

un- triggered display of two digital signals similar to Figure 60. Your scope

is actually triggering on random rising edges of channel- 1, which is the

scope’s default trigger condition. But these signals are too complex to

establish a unique trigger point using simple edge triggering. The signal

captured by channel-1 is an RS232 serial receive data signal (RX), and the

signal captured by channel- 2 is an RS232 serial transmit data signal (TX).

Let’s first set up the scope to intelligently decode this data stream based

on the RS232/UART protocol, and then we will establish a more unique

trigger point using RS232/UART triggering.

13 Press the [Serial] front panel key.

14 Press the Mode I

C softkey; then select the UART/RS232 serial decode

mode using the Entry knob.

15 Press the Signals softkey and verify that Rx is defined as channel- 1, and

that Tx is defined as channel- 2 (default conditions).

16 Press the (Back) front panel button (above power switch) to return

to the previous menu.

17 Press the Bus Config softkey.

18 Press the Parity softkey; then select Odd.

19 While this menu is active, also verity that the # of Bits is set to 8, the

Baud Rate is set to 19.2 kb/s, Polarity is set to Idle Low, and Bit Order is

set to LSB first.

Figure 60 Capturing RS232/UART transmit and receive data signals using the scope’s

Edge triggering mode.

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Agilent Technologies 3000 X-Series Manuel de service Page 86