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
2
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.
3
Triggering
Figure 4 shows the available selections for triggering
on RS-232/UART transmit and receive signals,
including triggering on either receive or transmit
parity errors.
In addition to being able to trigger on specific
transmit or receive bytes, this scope's "burst trigger"
mode allows you to specify to trigger on the "Nth"
byte within a burst of data bytes that satisfies the
data entry.
Real-time frame/byte totalizer
In addition to flagging parity errors, InfiniiVision’s
RS-232/UART option also provides a real-time
totalizer/counter of transmitted and received
frames/bytes, as shown in Figure 5. In addition, the
option allows you to count parity error bytes and
see a percent readout that gives an indication of
the quality of your serial bus. This totalize function,
which is not available in other oscilloscopes
currently on the market, is independent from the
scope’s acquisition or triggering. In addition, this
RS-232/UART byte counter is not affected by either
the oscilloscope’s acquisition window or scope deadtime. Totalize counts run continuously, even when
the scope’s acquisition is stopped.
Figure 4. Flexible triggering options enables you to trigger on
specific RS-232/UART receive or transmit strings.
Figure 5. InfiniiVision’s real-time totalizer counts all received and
transmitted bytes/frames, along with all parity errors.
4
Segmented memory captures more frames
The segmented memory option for Agilent’s
InfiniiVision Series oscilloscopes can optimize
your scope’s acquisition memory, allowing you
to capture more RS-232/UART signals using less
memory. Segmented memory acquisition optimizes
the number of packetized serial communication
frames/bytes that can be captured consecutively
by selectively ignoring (not digitizing) unimportant
idle time between frames. And with a minimum 250
picoseconds time-tagging resolution, you will know
the precise time between each frame.
Figure 6 shows an RS-232/UART measurement with
the scope set up to trigger on a receive start-bit
condition. Using this triggering condition with the
segmented memory acquisition mode turned on,
the scope easily captures 500 consecutive bursts of
serial communication for a total acquisition time of
11.5 seconds. After acquiring the 500 segments, we
can easily scroll through all frames individually to
look for any anomalies or errors.
Agilent’ s InfiniiVision Series oscilloscopes are
the only scopes on the market today that can
acquire segments on up to four analog channels
of acquisition, capture time-correlated segments
on digital channels of acquisition (using an MSO
model), and perform hardware-based serial bus
protocol decoding.
Segment 500
Segment 3
Segment 2
Segment 1
Figure 6. InfiniiVision’s segmented memory acquisition mode captures
more bytes while using less memory.
5
Performance characteristics
Performance characteristics
Tx and Rx source Analog channels 1, 2, 3, or 4
Digital channels D0 – D15 (on MSO models)
Bus configuration
Baud rates
Number of bits
Parity
Polarity
Bit order
Triggering Rx start bit
1200 bps up to 2.765 Mb/s (default = 19.2 kb/s)
5 to 9 (default = 8-bits)
None, odd, or even (default = None)
Idle low or idle high (default = Idle low)
LSB out first or MSB out first (default = LSB)
Rx stop bit
Rx data
Rx 1:data (9-bit format)
Rx 0:data (9-bit format)
Rx X:data (9-bit format)
Rx or Tx parity error
Tx start bit
Tx stop bit
Tx data
Tx 1:data (9-bit format)
Tx 0:data (9-bit format)
Tx X:data (9-bit format)
Burst (nth frame within burst defined by timeout)
Color-coded decode
Number of decode traces
Data format
Data byte display
Idle bus trace
Active bus trace
Totalize/counter function Total received frames
2 independent traces (1 for Tx, and 1 for Rx)
Binary, hex, or ASCII-code characters (default = Hex)
White characters if no parity error, red characters if parity or bus error
High or low trace in white (depends on polarity setting)
Byte-delimited bi-level trace in blue if no parity error, red if parity error
Total transmitted frames
Total parity error frames (with percentage)
6
Agilent InfiniiVision portfolio
Agilent’s InfiniiVision lineup includes 5000, 6000 and 7000 Series
oscilloscopes. These share a number of advanced hardware and
software technology blocks. Use the following selection guide to
determine which best matches your specific needs.
Largest display,
shallow depth
7000B Series
100 MHz Bandwidth ● ● ● ●
300/350 MHz Bandwidth ● ● ● ●
500 MHz Bandwidth ● ● ● ●
1 GHz Bandwidth ● ● ●
MSO Models ● ● ●
GPIB Connectivity ● ● ●
Rackmount height 7U 5U 1U 5U
Battery option ●
Display size 12.1” 6.3” 6.3”
Footprint (WxHxD) 17.9”x 10.9”x 6.8” 15.7”x 7.4”x 11.1” 17.1”x 1.7”x 10.6” 15.2”x 7.4”x 6.9”
Optional battery,
100 MHz MSO
6000A Series
Ideal for ATE rackmount
applications
6000L Series
Smallest form factor,
lowest price
5000 Series
Agilent’s InfiniiVision oscilloscope portfolio offers:
• A variety of form factors to fit your environment
• Responsive controls and best signal visibility
• Insightful application software
• Responsive deep memory with MegaZoom III
7
Ordering information
The N5457A RS-232/UART option
is compatible with all 4-channel
and 4+16-channel Agilent
InfiniiVision Series oscilloscopes
scopes). This option is available
as a factory-installed option if
ordered as Option-232 along with
a specific oscilloscope model,
or existing InfiniiVision Series
oscilloscope users can order
this option as an after-purchase
product upgrade (N5457A).
(5000, 6000, and 7000 Series
Model number –
user installed
N5457 232 RS-232/UART triggering and decode (for 4- and 4+16-channel scope models only)
N5423A LSS I
N5424A AMS CAN/LIN triggering and decode (for 4- and 4+16-channel scope models only)
N5432C FLX FlexRay triggering and decode (for 4- and 4+16 channel scope models only)
N5468A SND I
N5469A 553 MIL-STD 1553 triggering and decode (for 4- and 4+16 channel scope models only)
N5454A SGM Segmented memory
Note that additional options and accessories are available for Agilent InfiniiVision Series oscilloscopes. Refer to the appropriate 5000,
6000, or 7000 Series oscilloscope data sheet for ordering information about these additional options and accessories, as well as ordering
information for specific oscilloscope models.
Option number –
factory installed Description
2
C/SPI serial decode option (for 4- and 4+16-channel scope models only)
2
S triggering and decode (for 4- and 4+16 channel scope models only)
8
Related literature
Publication title Publication type Publication number
Agilent 7000B Series InfiniiVision Oscilloscopes
Agilent 6000 Series InfiniiVision Oscilloscopes
Agilent 5000 Series InfiniiVision Oscilloscopes
Agilent InfiniiVision Series Oscilloscope Probes and Accessories
Segmented Memory Acquisition (N5454A) for Agilent InfiniiVision Series Oscilloscopes
I2C and SPI Triggering and Hardware-Based Decode (N5423A) for Agilent InfiniiVision
Series Oscilloscopes
CAN/LIN Measurements (option AMS) for Agilent's InfiniiVision
Series Oscilloscopes
Evaluating Oscilloscope Segmented Memory for Serial Bus Applications
Evaluating Oscilloscopes for Best Waveform Update Rate
Evaluating Oscilloscopes to Debug Mixed-Signal Designs
Using an Agilent InfiniiVision MSO to Debug an Automotive CAN Bus
Evaluating Oscilloscope Bandwidths for your Applications
Evaluating Oscilloscope Sample Rates vs. Sampling Fidelity
Evaluating Oscilloscope Vertical Noise Characteristics
To download these documents, insert the publication number in the
URL: http://cp.literature.agilent.com/litweb/pdf/xxxx-xxxxEN.pdf
Data Sheet 5990-4769EN
Data Sheet 5989-2000EN
Data Sheet 5989-6110EN
Data Sheet 5968-8153EN
Data Sheet 5989-7833EN
Data Sheet 5989-5126EN
Data Sheet 5989-6220EN
Application Note 5989-7885EN
Application Note 5989-3702EN
Application Note 5989-5049EN
Application Note 5989-5049EN
Application Note 5989-5733EN
Application Note 5989-5732EN
Application Note 5989-3020EN
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October 1, 2009
© Agilent Technologies, Inc. 2010
Printed in USA, July 7, 2010
5989-7832EN
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