Data Sheet

8 Protocol Decoding RIGOL
MSO4000D/S4000 User’s Guide
8-5
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
Industry standard 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 also 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.
b
i
t
0
b
i
t
1
b
i
t
2
b
i
t
3
b
i
t
4
b
i
t
5
b
i
t
6
b
i
t
7
t
b
i
t
7
b
i
t
6
b
i
t
5
b
i
t
4
b
i
t
3
b
i
t
2
b
i
t
1
b
i
t
0
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 2400bps, 4800bps,
9600bps, 19200bps, 38400bps, 57600bps and 115200bps.