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
. 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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