Tektronix MDO3012, Руководство пользователя

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Acquire the Signal
Physical Layer Bus Activity
Oscilloscope waveform traces from analog channels 1 to 4, digital channels D15 to D0, Math waveforms, and the traces you
see when you choose to display a bus always show the physical layer bus activity. In the physical layer display, bits that were
transmitted earlier are to the left, and bits that were transmitted later are to the right.
I
2
C, and CAN and CAN FD buses transmit the MSB (most signi fi cant bit) fi rst
SPI buses do not specify a bit order
RS-232 and LIN buses transmit the LSB (least signi fi cant bit) fi rst
NOTE. The oscilloscope displays the decode traces and event tables for all buses with the MSB on the left and LSB
on the right.
For example, an RS-232 signal (after the start bit) might be high, high, high, low, high, low, low, and high. Since the RS-232
protocol uses high for zero and low for one, this value would be 0001 0110.
Since the decode displays the MSB fi rst, the oscilloscope reverses the order of the bits and displays 0110 1000. If the bus
display is set to hex, the value displays as 68. If the bus display is set to ASCII, the value displays as h.
Event Table
In addition to seeing decoded packet data on the bus waveform itself, you can view all captured packets in a tabular
view much like you would see in a software listing. Packets are time stamped and listed consecutively with columns for
each component (Address, Data, etc.). You can save the event table data in .CSV format for detailed of
fl ine analysis.
Using the Event Table, you can:
Scroll the event table to update the view point in the waveform.
Each row in the event table represents a time-stamped byte, packet, or word, depending on the bus type. As you scroll
the event table using the multipurpose knob, the view point in the oscilloscope display updates to show the position in the
waveform corresponding to the event in the Event Table.
Save the event table. (See page 68, Setting Up Bus Parameters .)
Saving an event table may save more data than can be presented on the oscilloscope. Use these saved fi les for
in-depth of fl ine analysis.
80 MDO3000 Series Oscilloscopes User Manual