Keysight Technologies DSO-X 2002A, User Manual

Page: 337 / 352

UART/RS232 Triggering and Serial Decode
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Keysight InfiniiVision 2000 X-Series Oscilloscopes User's Guide 337
UART/RS232 Triggering
To set up the oscilloscope to capture UART/RS-232 signals, see “Setup for
UART/RS232 Signals" on page 335.
To trigger on a UART (Universal Asynchronous Receiver/Transmitter) signal
connect the oscilloscope to the Rx and Tx lines and set up a trigger condition.
RS232 (Recommended Standard 232) is one example of a UART protocol.
1 Press [Trigger] .
2 In the Trigger Menu, press the Trigger softkey; then, turn the Entry knob to
select the serial slot (Serial 1) on which the UART/RS232 signals are being
decoded.
3 Press the Trigger Setup softkey to open the UART/RS232 Trigger Setup Menu.
4 Press the Base softkey to select Hex or ASCII as the base displayed on the Data
softkey in the UART/RS232 Trigger Setup Menu.
Note that the setting of this softkey does not affect the selected base of the
decode display.
5 Press the Trigger softkey and set up the desired trigger condition:
• Rx Start Bit — The oscilloscope triggers when a start bit occurs on Rx.
• Rx Stop Bit — Triggers when a stop bit occurs on Rx. The trigger will occur on
the first stop bit. This is done automatically whether the device under test
uses 1, 1.5, or 2 stop bits. You do not need to specify the number of stop bits
used by the device Under test.
• Rx Data — Triggers on a data byte that you specify. For use when the device
under test data words are from 5 to 8 bits in length (no 9th (alert) bit).