RIGOL DS6000 Series - Manual (Page 163)

7 Protocol Decoding RIGOL
DS6000 User’s Guide 7-5
RS232 Decoding (Option)
RS232 serial bus consists of the transmitting data line (TX) and the receiving data
line (RX).
DeviceA DeviceB
Tx Rx
Rx Tx
The industry standard of RS232 uses “Negative Logic”, namely high level is logic “0”
and low level is logic “1”.
1
0 0 0 0
1 1 1 1 1
By default, RS232 uses LSB (Least Significant Bit) transmission sequence, namely
the lowest bit of the data is transmitted first. While for MSB (Most Significant Bit),
the highest bit of the data is transmitted first.
Bit
0
Bit
5
Bit
2
Bit
3
Bit
6
Bit
1
Bit
7
Bit
4
t
Bit
7
Bit
2
Bit
5
Bit
4
Bit
1
Bit
6
Bit
0
Bit
3
t
Endian (LSB) Endian (MSB)
In RS232, baud rate is used to represent the transmitting rate (namely bits per
second) of the data. The commonly used baud rates include 2400 bps, 4800 bps,
9600 bps, 19200 bps, 38400 bps, 57600 bps and 115200 bps.
In RS232, you need to set the start bit, the data bits, the check bit (optional) and the
stop bit of each frame of data.