Technical data

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
2
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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