Acquire the Sign
al
Physical Layer Bus Activity
Oscilloscope waveform traces from analog channels 1 to 4, digital channels D15 to D0, 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.
I2C, and CAN buses transmit the MSB (most significant bit) first
SPI buses do not specify a bit order
RS-232 and LIN buses transmit the LSB (least significant bit) first
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 first, 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.
RS-232
If you defined an end-of-packet character
to use for RS-232 decoding, the stream of
bytes will be displayed as packets.
When decoding an RS-232 bus in ASCII
mode, a large dot indicates that the value
represents a character outside the printable
ASCII range.
58 MSO2000B and DPO2000B Series Oscilloscopes User Manual
To Next Page
Loading...
Need help?
General
