Find and debug intermittent errors and
signal integrity problems faster
RS-232/UART Triggering and
Hardware-Based Decode
(N5457A) for Agilent InfiniiVision
Oscilloscopes
Data Sheet
Features:
• RS-232/UART serial bus
triggering
• RS-232/UART hardware-based
protocol decoding
• Real-time frame and error
totalize counters
Introduction
Debugging systems that use an RS-232 serial bus
can be difficult, unless your scope is capable of
triggering on and decoding the RS-232 protocol.
Traditional methods of debugging serial buses such
as RS-232 include manual bit counting. But this
visual technique of counting “1s” and “0s” can be
tedious and it is prone to errors.
Agilent Technologies’ serial bus options for
InfiniiVision oscilloscopes offer powerful triggering
and provide unique hardware-accelerated decoding
to help you debug embedded designs with RS-232
and UART serial buses faster. With the industry’s
fastest serial decode update rates, you can more
easily find and debug random and intermittent
errors and signal integrity problems that you could
easily miss using other serial bus decode tools.
Other oscilloscope solutions with serial bus
triggering and protocol decode typically use
software post-processing techniques to decode
serial packets/frames. Using these software
techniques, waveform- and decode-update rates
tend to be slow (sometimes seconds per update),
especially when you use deep memory, which is
often required to capture multiple packetized
serial signals.
Figure 1. Defining the RS232/UART protocol structure
Bus configuration
The RS-232/UART option for Agilent InfiniiVision
Series scopes supports a broad range of protocol
structures including many RS-422 and RS-485
applications, as shown in Figure 1. Setting up an
InfiniiVision Series scope to trigger on and decode
your particular RS-232 or UART bus is easy. You can
select the following settings:
• Number of bits = 5 to 8
• Parity selection = None, odd, or even
• Baud rate = 1200 b/s up to 2.7648 Mb/s
• Polarity = Idle low or Idle high
• Bit order = LSB out first, or MSB out first
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RS-232/UART protocol decoding formats
You can serially decode transmit and receive signals
in either binary, hex, or ASCII format. The protocol
decode data is always displayed in a time-correlated
trace below the captured waveforms. In addition,
the decoded data can also be viewed in a tabular
format using the "lister" display mode. Figure 2
shows a transmit and receive message decoded in
hex format.
Figure 3 shows the same message decoded in
a color-coded ASCII format. Note the red “1”
character at the end of this important message. Red
is an indication that a parity error was detected for
that particular byte.
Figure 2. InfiniiVision Series scopes provide flexible RS-232/
UART decoding formats including binary, hex, and ASCII.
And with Agilent's 7000B Series oscilloscope, you
can also easily search and navigate within the
protocol lister display to find and mark particular
events of interest with direct time-correlation to the
waveform display.
Parity error
color-coded
in red
Figure 3. Color-coded ASCII decoding makes reading a
transmitted or received message much easier.
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